openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity
902,259 Commits 19 Branches 27 Tags 3.4 GiB
Commit Graph

2758 Commits

Author SHA1 Message Date
Vincent Guittot c63be7be59 sched/fair: Use utilization to select misfit task 
Utilization is used to detect a misfit task but the load is then used to
select the task on the CPU which can lead to select a small task with
high weight instead of the task that triggered the misfit migration.

Check that task can't fit the CPU's capacity when selecting the misfit
task instead of using the load.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Valentin Schneider <valentin.schneider@arm.com>
Cc: Ben Segall <bsegall@google.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: hdanton@sina.com
Cc: parth@linux.ibm.com
Cc: pauld@redhat.com
Cc: quentin.perret@arm.com
Cc: riel@surriel.com
Cc: srikar@linux.vnet.ibm.com
Link: https://lkml.kernel.org/r/1571405198-27570-9-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-10-21 09:40:54 +02:00
Vincent Guittot 2ab4092fc8 sched/fair: Spread out tasks evenly when not overloaded 
When there is only one CPU per group, using the idle CPUs to evenly spread
tasks doesn't make sense and nr_running is a better metrics.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: hdanton@sina.com
Cc: parth@linux.ibm.com
Cc: pauld@redhat.com
Cc: quentin.perret@arm.com
Cc: riel@surriel.com
Cc: srikar@linux.vnet.ibm.com
Cc: valentin.schneider@arm.com
Link: https://lkml.kernel.org/r/1571405198-27570-8-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-10-21 09:40:54 +02:00
Vincent Guittot b0fb1eb4f0 sched/fair: Use load instead of runnable load in load_balance() 
'runnable load' was originally introduced to take into account the case
where blocked load biases the load balance decision which was selecting
underutilized groups with huge blocked load whereas other groups were
overloaded.

The load is now only used when groups are overloaded. In this case,
it's worth being conservative and taking into account the sleeping
tasks that might wake up on the CPU.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: hdanton@sina.com
Cc: parth@linux.ibm.com
Cc: pauld@redhat.com
Cc: quentin.perret@arm.com
Cc: riel@surriel.com
Cc: srikar@linux.vnet.ibm.com
Cc: valentin.schneider@arm.com
Link: https://lkml.kernel.org/r/1571405198-27570-7-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-10-21 09:40:54 +02:00
Vincent Guittot 5e23e47443 sched/fair: Use rq->nr_running when balancing load 
CFS load_balance() only takes care of CFS tasks whereas CPUs can be used by
other scheduling classes. Typically, a CFS task preempted by an RT or deadline
task will not get a chance to be pulled by another CPU because
load_balance() doesn't take into account tasks from other classes.
Add sum of nr_running in the statistics and use it to detect such
situations.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: hdanton@sina.com
Cc: parth@linux.ibm.com
Cc: pauld@redhat.com
Cc: quentin.perret@arm.com
Cc: riel@surriel.com
Cc: srikar@linux.vnet.ibm.com
Cc: valentin.schneider@arm.com
Link: https://lkml.kernel.org/r/1571405198-27570-6-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-10-21 09:40:54 +02:00
Vincent Guittot 0b0695f2b3 sched/fair: Rework load_balance() 
The load_balance() algorithm contains some heuristics which have become
meaningless since the rework of the scheduler's metrics like the
introduction of PELT.

Furthermore, load is an ill-suited metric for solving certain task
placement imbalance scenarios.

For instance, in the presence of idle CPUs, we should simply try to get at
least one task per CPU, whereas the current load-based algorithm can actually
leave idle CPUs alone simply because the load is somewhat balanced.

The current algorithm ends up creating virtual and meaningless values like
the avg_load_per_task or tweaks the state of a group to make it overloaded
whereas it's not, in order to try to migrate tasks.

load_balance() should better qualify the imbalance of the group and clearly
define what has to be moved to fix this imbalance.

The type of sched_group has been extended to better reflect the type of
imbalance. We now have:

	group_has_spare
	group_fully_busy
	group_misfit_task
	group_asym_packing
	group_imbalanced
	group_overloaded

Based on the type of sched_group, load_balance now sets what it wants to
move in order to fix the imbalance. It can be some load as before but also
some utilization, a number of task or a type of task:

	migrate_task
	migrate_util
	migrate_load
	migrate_misfit

This new load_balance() algorithm fixes several pending wrong tasks
placement:

 - the 1 task per CPU case with asymmetric system
 - the case of cfs task preempted by other class
 - the case of tasks not evenly spread on groups with spare capacity

Also the load balance decisions have been consolidated in the 3 functions
below after removing the few bypasses and hacks of the current code:

 - update_sd_pick_busiest() select the busiest sched_group.
 - find_busiest_group() checks if there is an imbalance between local and
   busiest group.
 - calculate_imbalance() decides what have to be moved.

Finally, the now unused field total_running of struct sd_lb_stats has been
removed.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: hdanton@sina.com
Cc: parth@linux.ibm.com
Cc: pauld@redhat.com
Cc: quentin.perret@arm.com
Cc: riel@surriel.com
Cc: srikar@linux.vnet.ibm.com
Cc: valentin.schneider@arm.com
Link: https://lkml.kernel.org/r/1571405198-27570-5-git-send-email-vincent.guittot@linaro.org
[ Small readability and spelling updates. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-10-21 09:40:53 +02:00
Vincent Guittot fcf0553db6 sched/fair: Remove meaningless imbalance calculation 
Clean up load_balance() and remove meaningless calculation and fields before
adding a new algorithm.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Ben Segall <bsegall@google.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: hdanton@sina.com
Cc: parth@linux.ibm.com
Cc: pauld@redhat.com
Cc: quentin.perret@arm.com
Cc: srikar@linux.vnet.ibm.com
Cc: valentin.schneider@arm.com
Link: https://lkml.kernel.org/r/1571405198-27570-4-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-10-21 09:40:53 +02:00
Vincent Guittot a349834703 sched/fair: Rename sg_lb_stats::sum_nr_running to sum_h_nr_running 
Rename sum_nr_running to sum_h_nr_running because it effectively tracks
cfs->h_nr_running so we can use sum_nr_running to track rq->nr_running
when needed.

There are no functional changes.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Ben Segall <bsegall@google.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: hdanton@sina.com
Cc: parth@linux.ibm.com
Cc: pauld@redhat.com
Cc: quentin.perret@arm.com
Cc: srikar@linux.vnet.ibm.com
Link: https://lkml.kernel.org/r/1571405198-27570-3-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-10-21 09:40:53 +02:00
Vincent Guittot 490ba971d8 sched/fair: Clean up asym packing 
Clean up asym packing to follow the default load balance behavior:

- classify the group by creating a group_asym_packing field.
- calculate the imbalance in calculate_imbalance() instead of bypassing it.

We don't need to test twice same conditions anymore to detect asym packing
and we consolidate the calculation of imbalance in calculate_imbalance().

There is no functional changes.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Ben Segall <bsegall@google.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: hdanton@sina.com
Cc: parth@linux.ibm.com
Cc: pauld@redhat.com
Cc: quentin.perret@arm.com
Cc: srikar@linux.vnet.ibm.com
Cc: valentin.schneider@arm.com
Link: https://lkml.kernel.org/r/1571405198-27570-2-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-10-21 09:40:53 +02:00
Valentin Schneider 9ae7ab20b4 sched/topology: Don't set SD_BALANCE_WAKE on cpuset domain relax 
As pointed out in commit

  182a85f8a1 ("sched: Disable wakeup balancing")

SD_BALANCE_WAKE is a tad too aggressive, and is usually left unset.

However, it turns out cpuset domain relaxation will unconditionally set it
on domains below the relaxation level. This made sense back when
SD_BALANCE_WAKE was set unconditionally, but it no longer is the case.

We can improve things slightly by noticing that set_domain_attribute() is
always called after sd_init(), so rather than setting flags we can rely on
whatever sd_init() is doing and only clear certain flags when above the
relaxation level.

While at it, slightly clean up the function and flip the relax level
check to be more human readable.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: mingo@kernel.org
Cc: vincent.guittot@linaro.org
Cc: juri.lelli@redhat.com
Cc: seto.hidetoshi@jp.fujitsu.com
Cc: qperret@google.com
Cc: Dietmar.Eggemann@arm.com
Cc: morten.rasmussen@arm.com
Link: https://lkml.kernel.org/r/20191014164408.32596-1-valentin.schneider@arm.com
 2019-10-17 21:31:54 +02:00
Linus Torvalds 328fefadd9 Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 
Pull scheduler fixes from Ingo Molnar:
 "Two fixes: a guest-cputime accounting fix, and a cgroup bandwidth
  quota precision fix"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/vtime: Fix guest/system mis-accounting on task switch
  sched/fair: Scale bandwidth quota and period without losing quota/period ratio precision
 2019-10-12 15:29:54 -07:00
Qian Cai 5facae4f35 locking/lockdep: Remove unused @nested argument from lock_release() 
Since the following commit:

  b4adfe8e05 ("locking/lockdep: Remove unused argument in __lock_release")

@nested is no longer used in lock_release(), so remove it from all
lock_release() calls and friends.

Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: airlied@linux.ie
Cc: akpm@linux-foundation.org
Cc: alexander.levin@microsoft.com
Cc: daniel@iogearbox.net
Cc: davem@davemloft.net
Cc: dri-devel@lists.freedesktop.org
Cc: duyuyang@gmail.com
Cc: gregkh@linuxfoundation.org
Cc: hannes@cmpxchg.org
Cc: intel-gfx@lists.freedesktop.org
Cc: jack@suse.com
Cc: jlbec@evilplan.or
Cc: joonas.lahtinen@linux.intel.com
Cc: joseph.qi@linux.alibaba.com
Cc: jslaby@suse.com
Cc: juri.lelli@redhat.com
Cc: maarten.lankhorst@linux.intel.com
Cc: mark@fasheh.com
Cc: mhocko@kernel.org
Cc: mripard@kernel.org
Cc: ocfs2-devel@oss.oracle.com
Cc: rodrigo.vivi@intel.com
Cc: sean@poorly.run
Cc: st@kernel.org
Cc: tj@kernel.org
Cc: tytso@mit.edu
Cc: vdavydov.dev@gmail.com
Cc: vincent.guittot@linaro.org
Cc: viro@zeniv.linux.org.uk
Link: https://lkml.kernel.org/r/1568909380-32199-1-git-send-email-cai@lca.pw
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-10-09 12:46:10 +02:00
Frederic Weisbecker 8d495477d6 sched/cputime: Spare a seqcount lock/unlock cycle on context switch 
On context switch we are locking the vtime seqcount of the scheduling-out
task twice:

 * On vtime_task_switch_common(), when we flush the pending vtime through
   vtime_account_system()

 * On arch_vtime_task_switch() to reset the vtime state.

This is pointless as these actions can be performed without the need
to unlock/lock in the middle. The reason these steps are separated is to
consolidate a very small amount of common code between
CONFIG_VIRT_CPU_ACCOUNTING_GEN and CONFIG_VIRT_CPU_ACCOUNTING_NATIVE.

Performance in this fast path is definitely a priority over artificial
code factorization so split the task switch code between GEN and
NATIVE and mutualize the parts than can run under a single seqcount
locked block.

As a side effect, vtime_account_idle() becomes included in the seqcount
protection. This happens to be a welcome preparation in order to
properly support kcpustat under vtime in the future and fetch
CPUTIME_IDLE without race.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Link: https://lkml.kernel.org/r/20191003161745.28464-3-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-10-09 12:39:26 +02:00
Frederic Weisbecker f83eeb1a01 sched/cputime: Rename vtime_account_system() to vtime_account_kernel() 
vtime_account_system() decides if we need to account the time to the
system (__vtime_account_system()) or to the guest (vtime_account_guest()).

So this function is a misnomer as we are on a higher level than
"system". All we know when we call that function is that we are
accounting kernel cputime. Whether it belongs to guest or system time
is a lower level detail.

Rename this function to vtime_account_kernel(). This will clarify things
and avoid too many underscored vtime_account_system() versions.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Link: https://lkml.kernel.org/r/20191003161745.28464-2-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-10-09 12:39:25 +02:00
Frederic Weisbecker 68e7a4d66b sched/vtime: Fix guest/system mis-accounting on task switch 
vtime_account_system() assumes that the target task to account cputime
to is always the current task. This is most often true indeed except on
task switch where we call:

	vtime_common_task_switch(prev)
		vtime_account_system(prev)

Here prev is the scheduling-out task where we account the cputime to. It
doesn't match current that is already the scheduling-in task at this
stage of the context switch.

So we end up checking the wrong task flags to determine if we are
accounting guest or system time to the previous task.

As a result the wrong task is used to check if the target is running in
guest mode. We may then spuriously account or leak either system or
guest time on task switch.

Fix this assumption and also turn vtime_guest_enter/exit() to use the
task passed in parameter as well to avoid future similar issues.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpengli@tencent.com>
Fixes: 2a42eb9594 ("sched/cputime: Accumulate vtime on top of nsec clocksource")
Link: https://lkml.kernel.org/r/20190925214242.21873-1-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-10-09 12:38:03 +02:00
Xuewei Zhang 4929a4e6fa sched/fair: Scale bandwidth quota and period without losing quota/period ratio precision 
The quota/period ratio is used to ensure a child task group won't get
more bandwidth than the parent task group, and is calculated as:

  normalized_cfs_quota() = [(quota_us << 20) / period_us]

If the quota/period ratio was changed during this scaling due to
precision loss, it will cause inconsistency between parent and child
task groups.

See below example:

A userspace container manager (kubelet) does three operations:

 1) Create a parent cgroup, set quota to 1,000us and period to 10,000us.
 2) Create a few children cgroups.
 3) Set quota to 1,000us and period to 10,000us on a child cgroup.

These operations are expected to succeed. However, if the scaling of
147/128 happens before step 3, quota and period of the parent cgroup
will be changed:

  new_quota: 1148437ns,   1148us
 new_period: 11484375ns, 11484us

And when step 3 comes in, the ratio of the child cgroup will be
104857, which will be larger than the parent cgroup ratio (104821),
and will fail.

Scaling them by a factor of 2 will fix the problem.

Tested-by: Phil Auld <pauld@redhat.com>
Signed-off-by: Xuewei Zhang <xueweiz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Phil Auld <pauld@redhat.com>
Cc: Anton Blanchard <anton@ozlabs.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Fixes: 2e8e192263 ("sched/fair: Limit sched_cfs_period_timer() loop to avoid hard lockup")
Link: https://lkml.kernel.org/r/20191004001243.140897-1-xueweiz@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-10-09 12:38:02 +02:00
Linus Torvalds e524d16e7e copy-struct-from-user-v5.4-rc2 
-----BEGIN PGP SIGNATURE-----
 
 iHUEABYKAB0WIQRAhzRXHqcMeLMyaSiRxhvAZXjcogUCXZZIgQAKCRCRxhvAZXjc
 orNOAP98B2nmoxvq8d5Z6PhoyTBC5NIUuJ5h2YMwcX/hAaj5uQEA58NTKtPmOPDR
 2ffUFFerGZ2+brlHgACa0ZKdH27TjAA=
 =QryD
 -----END PGP SIGNATURE-----

Merge tag 'copy-struct-from-user-v5.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

Pull copy_struct_from_user() helper from Christian Brauner:
 "This contains the copy_struct_from_user() helper which got split out
  from the openat2() patchset. It is a generic interface designed to
  copy a struct from userspace.

  The helper will be especially useful for structs versioned by size of
  which we have quite a few. This allows for backwards compatibility,
  i.e. an extended struct can be passed to an older kernel, or a legacy
  struct can be passed to a newer kernel. For the first case (extended
  struct, older kernel) the new fields in an extended struct can be set
  to zero and the struct safely passed to an older kernel.

  The most obvious benefit is that this helper lets us get rid of
  duplicate code present in at least sched_setattr(), perf_event_open(),
  and clone3(). More importantly it will also help to ensure that users
  implementing versioning-by-size end up with the same core semantics.

  This point is especially crucial since we have at least one case where
  versioning-by-size is used but with slighly different semantics:
  sched_setattr(), perf_event_open(), and clone3() all do do similar
  checks to copy_struct_from_user() while rt_sigprocmask(2) always
  rejects differently-sized struct arguments.

  With this pull request we also switch over sched_setattr(),
  perf_event_open(), and clone3() to use the new helper"

* tag 'copy-struct-from-user-v5.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  usercopy: Add parentheses around assignment in test_copy_struct_from_user
  perf_event_open: switch to copy_struct_from_user()
  sched_setattr: switch to copy_struct_from_user()
  clone3: switch to copy_struct_from_user()
  lib: introduce copy_struct_from_user() helper
 2019-10-04 10:36:31 -07:00
Peter Zijlstra 73956fc07d membarrier: Fix RCU locking bug caused by faulty merge 
The following commit:

  227a4aadc7 ("sched/membarrier: Fix p->mm->membarrier_state racy load")

got fat fingered by me when merging it with other patches. It meant to move
the RCU section out of the for loop but ended up doing it partially, leaving
a superfluous rcu_read_lock() inside, causing havok.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-tip-commits@vger.kernel.org
Fixes: 227a4aadc7 ("sched/membarrier: Fix p->mm->membarrier_state racy load")
Link: https://lkml.kernel.org/r/20191001085033.GP4519@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-10-01 21:27:50 +02:00
Aleksa Sarai dff3a85fec sched_setattr: switch to copy_struct_from_user() 
Switch sched_setattr() syscall from it's own copying struct sched_attr
from userspace to the new dedicated copy_struct_from_user() helper.

The change is very straightforward, and helps unify the syscall
interface for struct-from-userspace syscalls. Ideally we could also
unify sched_getattr(2)-style syscalls as well, but unfortunately the
correct semantics for such syscalls are much less clear (see [1] for
more detail). In future we could come up with a more sane idea for how
the syscall interface should look.

[1]: commit 1251201c0d ("sched/core: Fix uclamp ABI bug, clean up and
     robustify sched_read_attr() ABI logic and code")

Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>
[christian.brauner@ubuntu.com: improve commit message]
Link: https://lore.kernel.org/r/20191001011055.19283-4-cyphar@cyphar.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
 2019-10-01 15:45:17 +02:00
Linus Torvalds 9c5efe9ae7 Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 
Pull scheduler fixes from Ingo Molnar:

 - Apply a number of membarrier related fixes and cleanups, which fixes
   a use-after-free race in the membarrier code

 - Introduce proper RCU protection for tasks on the runqueue - to get
   rid of the subtle task_rcu_dereference() interface that was easy to
   get wrong

 - Misc fixes, but also an EAS speedup

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Avoid redundant EAS calculation
  sched/core: Remove double update_max_interval() call on CPU startup
  sched/core: Fix preempt_schedule() interrupt return comment
  sched/fair: Fix -Wunused-but-set-variable warnings
  sched/core: Fix migration to invalid CPU in __set_cpus_allowed_ptr()
  sched/membarrier: Return -ENOMEM to userspace on memory allocation failure
  sched/membarrier: Skip IPIs when mm->mm_users == 1
  selftests, sched/membarrier: Add multi-threaded test
  sched/membarrier: Fix p->mm->membarrier_state racy load
  sched/membarrier: Call sync_core only before usermode for same mm
  sched/membarrier: Remove redundant check
  sched/membarrier: Fix private expedited registration check
  tasks, sched/core: RCUify the assignment of rq->curr
  tasks, sched/core: With a grace period after finish_task_switch(), remove unnecessary code
  tasks, sched/core: Ensure tasks are available for a grace period after leaving the runqueue
  tasks: Add a count of task RCU users
  sched/core: Convert vcpu_is_preempted() from macro to an inline function
  sched/fair: Remove unused cfs_rq_clock_task() function
 2019-09-28 12:39:07 -07:00
Quentin Perret 4892f51ad5 sched/fair: Avoid redundant EAS calculation 
The EAS wake-up path computes the system energy for several CPU
candidates: the CPU with maximum spare capacity in each performance
domain, and the prev_cpu. However, if prev_cpu also happens to be the
CPU with maximum spare capacity in its performance domain, the energy
calculation is still done twice, unnecessarily.

Add a condition to filter out this corner case before doing the energy
calculation.

Reported-by: Pavan Kondeti <pkondeti@codeaurora.org>
Signed-off-by: Quentin Perret <qperret@qperret.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: juri.lelli@redhat.com
Cc: morten.rasmussen@arm.com
Cc: qais.yousef@arm.com
Cc: rjw@rjwysocki.net
Cc: tkjos@google.com
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Fixes: eb92692b25 ("sched/fair: Speed-up energy-aware wake-ups")
Link: https://lkml.kernel.org/r/20190920094115.GA11503@qperret.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-25 17:42:32 +02:00
Valentin Schneider 9fc41acc89 sched/core: Remove double update_max_interval() call on CPU startup 
update_max_interval() is called in both CPUHP_AP_SCHED_STARTING's startup
and teardown callbacks, but it turns out it's also called at the end of
the startup callback of CPUHP_AP_ACTIVE (which is further down the
startup sequence).

There's no point in repeating this interval update in the startup sequence
since the CPU will remain online until it goes down the teardown path.

Remove the redundant call in sched_cpu_activate() (CPUHP_AP_ACTIVE).

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: juri.lelli@redhat.com
Cc: vincent.guittot@linaro.org
Link: https://lkml.kernel.org/r/20190923093017.11755-1-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-25 17:42:32 +02:00
Valentin Schneider a49b4f4012 sched/core: Fix preempt_schedule() interrupt return comment 
preempt_schedule_irq() is the one that should be called on return from
interrupt, clean up the comment to avoid any ambiguity.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-m68k@lists.linux-m68k.org
Cc: linux-riscv@lists.infradead.org
Cc: uclinux-h8-devel@lists.sourceforge.jp
Link: https://lkml.kernel.org/r/20190923143620.29334-2-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-25 17:42:32 +02:00
Qian Cai 763a9ec06c sched/fair: Fix -Wunused-but-set-variable warnings 
Commit:

   de53fd7aed ("sched/fair: Fix low cpu usage with high throttling by removing expiration of cpu-local slices")

introduced a few compilation warnings:

  kernel/sched/fair.c: In function '__refill_cfs_bandwidth_runtime':
  kernel/sched/fair.c:4365:6: warning: variable 'now' set but not used [-Wunused-but-set-variable]
  kernel/sched/fair.c: In function 'start_cfs_bandwidth':
  kernel/sched/fair.c:4992:6: warning: variable 'overrun' set but not used [-Wunused-but-set-variable]

Also, __refill_cfs_bandwidth_runtime() does no longer update the
expiration time, so fix the comments accordingly.

Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ben Segall <bsegall@google.com>
Reviewed-by: Dave Chiluk <chiluk+linux@indeed.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: pauld@redhat.com
Fixes: de53fd7aed ("sched/fair: Fix low cpu usage with high throttling by removing expiration of cpu-local slices")
Link: https://lkml.kernel.org/r/1566326455-8038-1-git-send-email-cai@lca.pw
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-25 17:42:31 +02:00
KeMeng Shi 714e501e16 sched/core: Fix migration to invalid CPU in __set_cpus_allowed_ptr() 
An oops can be triggered in the scheduler when running qemu on arm64:

 Unable to handle kernel paging request at virtual address ffff000008effe40
 Internal error: Oops: 96000007 [#1] SMP
 Process migration/0 (pid: 12, stack limit = 0x00000000084e3736)
 pstate: 20000085 (nzCv daIf -PAN -UAO)
 pc : __ll_sc___cmpxchg_case_acq_4+0x4/0x20
 lr : move_queued_task.isra.21+0x124/0x298
 ...
 Call trace:
  __ll_sc___cmpxchg_case_acq_4+0x4/0x20
  __migrate_task+0xc8/0xe0
  migration_cpu_stop+0x170/0x180
  cpu_stopper_thread+0xec/0x178
  smpboot_thread_fn+0x1ac/0x1e8
  kthread+0x134/0x138
  ret_from_fork+0x10/0x18

__set_cpus_allowed_ptr() will choose an active dest_cpu in affinity mask to
migrage the process if process is not currently running on any one of the
CPUs specified in affinity mask. __set_cpus_allowed_ptr() will choose an
invalid dest_cpu (dest_cpu >= nr_cpu_ids, 1024 in my virtual machine) if
CPUS in an affinity mask are deactived by cpu_down after cpumask_intersects
check. cpumask_test_cpu() of dest_cpu afterwards is overflown and may pass if
corresponding bit is coincidentally set. As a consequence, kernel will
access an invalid rq address associate with the invalid CPU in
migration_cpu_stop->__migrate_task->move_queued_task and the Oops occurs.

The reproduce the crash:

  1) A process repeatedly binds itself to cpu0 and cpu1 in turn by calling
  sched_setaffinity.

  2) A shell script repeatedly does "echo 0 > /sys/devices/system/cpu/cpu1/online"
  and "echo 1 > /sys/devices/system/cpu/cpu1/online" in turn.

  3) Oops appears if the invalid CPU is set in memory after tested cpumask.

Signed-off-by: KeMeng Shi <shikemeng@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/1568616808-16808-1-git-send-email-shikemeng@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-25 17:42:31 +02:00
Mathieu Desnoyers c172e0a3e8 sched/membarrier: Return -ENOMEM to userspace on memory allocation failure 
Remove the IPI fallback code from membarrier to deal with very
infrequent cpumask memory allocation failure. Use GFP_KERNEL rather
than GFP_NOWAIT, and relax the blocking guarantees for the expedited
membarrier system call commands, allowing it to block if waiting for
memory to be made available.

In addition, now -ENOMEM can be returned to user-space if the cpumask
memory allocation fails.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190919173705.2181-8-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-25 17:42:31 +02:00
Mathieu Desnoyers c6d68c1c4a sched/membarrier: Skip IPIs when mm->mm_users == 1 
If there is only a single mm_user for the mm, the private expedited
membarrier command can skip the IPIs, because only a single thread
is using the mm.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190919173705.2181-7-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-25 17:42:31 +02:00
Mathieu Desnoyers 227a4aadc7 sched/membarrier: Fix p->mm->membarrier_state racy load 
The membarrier_state field is located within the mm_struct, which
is not guaranteed to exist when used from runqueue-lock-free iteration
on runqueues by the membarrier system call.

Copy the membarrier_state from the mm_struct into the scheduler runqueue
when the scheduler switches between mm.

When registering membarrier for mm, after setting the registration bit
in the mm membarrier state, issue a synchronize_rcu() to ensure the
scheduler observes the change. In order to take care of the case
where a runqueue keeps executing the target mm without swapping to
other mm, iterate over each runqueue and issue an IPI to copy the
membarrier_state from the mm_struct into each runqueue which have the
same mm which state has just been modified.

Move the mm membarrier_state field closer to pgd in mm_struct to use
a cache line already touched by the scheduler switch_mm.

The membarrier_execve() (now membarrier_exec_mmap) hook now needs to
clear the runqueue's membarrier state in addition to clear the mm
membarrier state, so move its implementation into the scheduler
membarrier code so it can access the runqueue structure.

Add memory barrier in membarrier_exec_mmap() prior to clearing
the membarrier state, ensuring memory accesses executed prior to exec
are not reordered with the stores clearing the membarrier state.

As suggested by Linus, move all membarrier.c RCU read-side locks outside
of the for each cpu loops.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190919173705.2181-5-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-25 17:42:30 +02:00
Mathieu Desnoyers 09554009c0 sched/membarrier: Remove redundant check 
Checking that the number of threads is 1 is redundant with checking
mm_users == 1.

No change in functionality intended.

Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190919173705.2181-3-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-25 17:42:30 +02:00
Mathieu Desnoyers fc0d77387c sched/membarrier: Fix private expedited registration check 
Fix a logic flaw in the way membarrier_register_private_expedited()
handles ready state checks for private expedited sync core and private
expedited registrations.

If a private expedited membarrier registration is first performed, and
then a private expedited sync_core registration is performed, the ready
state check will skip the second registration when it really should not.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190919173705.2181-2-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-25 17:42:30 +02:00
Eric W. Biederman 5311a98fef tasks, sched/core: RCUify the assignment of rq->curr 
The current task on the runqueue is currently read with rcu_dereference().

To obtain ordinary RCU semantics for an rcu_dereference() of rq->curr it needs
to be paired with rcu_assign_pointer() of rq->curr.  Which provides the
memory barrier necessary to order assignments to the task_struct
and the assignment to rq->curr.

Unfortunately the assignment of rq->curr in __schedule is a hot path,
and it has already been show that additional barriers in that code
will reduce the performance of the scheduler.  So I will attempt to
describe below why you can effectively have ordinary RCU semantics
without any additional barriers.

The assignment of rq->curr in init_idle is a slow path called once
per cpu and that can use rcu_assign_pointer() without any concerns.

As I write this there are effectively two users of rcu_dereference() on
rq->curr.  There is the membarrier code in kernel/sched/membarrier.c
that only looks at "->mm" after the rcu_dereference().  Then there is
task_numa_compare() in kernel/sched/fair.c.  My best reading of the
code shows that task_numa_compare only access: "->flags",
"->cpus_ptr", "->numa_group", "->numa_faults[]",
"->total_numa_faults", and "->se.cfs_rq".

The code in __schedule() essentially does:
	rq_lock(...);
	smp_mb__after_spinlock();

	next = pick_next_task(...);
	rq->curr = next;

	context_switch(prev, next);

At the start of the function the rq_lock/smp_mb__after_spinlock
pair provides a full memory barrier.  Further there is a full memory barrier
in context_switch().

This means that any task that has already run and modified itself (the
common case) has already seen two memory barriers before __schedule()
runs and begins executing.  A task that modifies itself then sees a
third full memory barrier pair with the rq_lock();

For a brand new task that is enqueued with wake_up_new_task() there
are the memory barriers present from the taking and release the
pi_lock and the rq_lock as the processes is enqueued as well as the
full memory barrier at the start of __schedule() assuming __schedule()
happens on the same cpu.

This means that by the time we reach the assignment of rq->curr
except for values on the task struct modified in pick_next_task
the code has the same guarantees as if it used rcu_assign_pointer().

Reading through all of the implementations of pick_next_task it
appears pick_next_task is limited to modifying the task_struct fields
"->se", "->rt", "->dl".  These fields are the sched_entity structures
of the varies schedulers.

Further "->se.cfs_rq" is only changed in cgroup attach/move operations
initialized by userspace.

Unless I have missed something this means that in practice that the
users of "rcu_dereference(rq->curr)" get normal RCU semantics of
rcu_dereference() for the fields the care about, despite the
assignment of rq->curr in __schedule() ot using rcu_assign_pointer.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20190903200603.GW2349@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-25 17:42:29 +02:00
Eric W. Biederman 154abafc68 tasks, sched/core: With a grace period after finish_task_switch(), remove unnecessary code 
Remove work arounds that were written before there was a grace period
after tasks left the runqueue in finish_task_switch().

In particular now that there tasks exiting the runqueue exprience
a RCU grace period none of the work performed by task_rcu_dereference()
excpet the rcu_dereference() is necessary so replace task_rcu_dereference()
with rcu_dereference().

Remove the code in rcuwait_wait_event() that checks to ensure the current
task has not exited.  It is no longer necessary as it is guaranteed
that any running task will experience a RCU grace period after it
leaves the run queueue.

Remove the comment in rcuwait_wake_up() as it is no longer relevant.

Ref: 8f95c90ceb ("sched/wait, RCU: Introduce rcuwait machinery")
Ref: 150593bf86 ("sched/api: Introduce task_rcu_dereference() and try_get_task_struct()")
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/87lfurdpk9.fsf_-_@x220.int.ebiederm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-25 17:42:29 +02:00
Eric W. Biederman 0ff7b2cfba tasks, sched/core: Ensure tasks are available for a grace period after leaving the runqueue 
In the ordinary case today the RCU grace period for a task_struct is
triggered when another process wait's for it's zombine and causes the
kernel to call release_task().  As the waiting task has to receive a
signal and then act upon it before this happens, typically this will
occur after the original task as been removed from the runqueue.

Unfortunaty in some cases such as self reaping tasks it can be shown
that release_task() will be called starting the grace period for
task_struct long before the task leaves the runqueue.

Therefore use put_task_struct_rcu_user() in finish_task_switch() to
guarantee that the there is a RCU lifetime after the task
leaves the runqueue.

Besides the change in the start of the RCU grace period for the
task_struct this change may cause perf_event_delayed_put and
trace_sched_process_free.  The function perf_event_delayed_put boils
down to just a WARN_ON for cases that I assume never show happen.  So
I don't see any problem with delaying it.

The function trace_sched_process_free is a trace point and thus
visible to user space.  Occassionally userspace has the strangest
dependencies so this has a miniscule chance of causing a regression.
This change only changes the timing of when the tracepoint is called.
The change in timing arguably gives userspace a more accurate picture
of what is going on.  So I don't expect there to be a regression.

In the case where a task self reaps we are pretty much guaranteed that
the RCU grace period is delayed.  So we should get quite a bit of
coverage in of this worst case for the change in a normal threaded
workload.  So I expect any issues to turn up quickly or not at all.

I have lightly tested this change and everything appears to work
fine.

Inspired-by: Linus Torvalds <torvalds@linux-foundation.org>
Inspired-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/87r24jdpl5.fsf_-_@x220.int.ebiederm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-25 17:42:29 +02:00
Nicholas Piggin 13224794cb mm: remove quicklist page table caches 
Patch series "mm: remove quicklist page table caches".

A while ago Nicholas proposed to remove quicklist page table caches [1].

I've rebased his patch on the curren upstream and switched ia64 and sh to
use generic versions of PTE allocation.

[1] https://lore.kernel.org/linux-mm/20190711030339.20892-1-npiggin@gmail.com

This patch (of 3):

Remove page table allocator "quicklists".  These have been around for a
long time, but have not got much traction in the last decade and are only
used on ia64 and sh architectures.

The numbers in the initial commit look interesting but probably don't
apply anymore.  If anybody wants to resurrect this it's in the git
history, but it's unhelpful to have this code and divergent allocator
behaviour for minor archs.

Also it might be better to instead make more general improvements to page
allocator if this is still so slow.

Link: http://lkml.kernel.org/r/1565250728-21721-2-git-send-email-rppt@linux.ibm.com
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-09-24 15:54:09 -07:00
Linus Torvalds 84da111de0 hmm related patches for 5.4 
This is more cleanup and consolidation of the hmm APIs and the very
 strongly related mmu_notifier interfaces. Many places across the tree
 using these interfaces are touched in the process. Beyond that a cleanup
 to the page walker API and a few memremap related changes round out the
 series:
 
 - General improvement of hmm_range_fault() and related APIs, more
   documentation, bug fixes from testing, API simplification &
   consolidation, and unused API removal
 
 - Simplify the hmm related kconfigs to HMM_MIRROR and DEVICE_PRIVATE, and
   make them internal kconfig selects
 
 - Hoist a lot of code related to mmu notifier attachment out of drivers by
   using a refcount get/put attachment idiom and remove the convoluted
   mmu_notifier_unregister_no_release() and related APIs.
 
 - General API improvement for the migrate_vma API and revision of its only
   user in nouveau
 
 - Annotate mmu_notifiers with lockdep and sleeping region debugging
 
 Two series unrelated to HMM or mmu_notifiers came along due to
 dependencies:
 
 - Allow pagemap's memremap_pages family of APIs to work without providing
   a struct device
 
 - Make walk_page_range() and related use a constant structure for function
   pointers
 -----BEGIN PGP SIGNATURE-----
 
 iQIzBAABCgAdFiEEfB7FMLh+8QxL+6i3OG33FX4gmxoFAl1/nnkACgkQOG33FX4g
 mxqaRg//c6FqowV1pQlLutvAOAgMdpzfZ9eaaDKngy9RVQxz+k/MmJrdRH/p/mMA
 Pq93A1XfwtraGKErHegFXGEDk4XhOustVAVFwvjyXO41dTUdoFVUkti6ftbrl/rS
 6CT+X90jlvrwdRY7QBeuo7lxx7z8Qkqbk1O1kc1IOracjKfNJS+y6LTamy6weM3g
 tIMHI65PkxpRzN36DV9uCN5dMwFzJ73DWHp1b0acnDIigkl6u5zp6orAJVWRjyQX
 nmEd3/IOvdxaubAoAvboNS5CyVb4yS9xshWWMbH6AulKJv3Glca1Aa7QuSpBoN8v
 wy4c9+umzqRgzgUJUe1xwN9P49oBNhJpgBSu8MUlgBA4IOc3rDl/Tw0b5KCFVfkH
 yHkp8n6MP8VsRrzXTC6Kx0vdjIkAO8SUeylVJczAcVSyHIo6/JUJCVDeFLSTVymh
 EGWJ7zX2iRhUbssJ6/izQTTQyCH3YIyZ5QtqByWuX2U7ZrfkqS3/EnBW1Q+j+gPF
 Z2yW8iT6k0iENw6s8psE9czexuywa/Lttz94IyNlOQ8rJTiQqB9wLaAvg9hvUk7a
 kuspL+JGIZkrL3ouCeO/VA6xnaP+Q7nR8geWBRb8zKGHmtWrb5Gwmt6t+vTnCC2l
 olIDebrnnxwfBQhEJ5219W+M1pBpjiTpqK/UdBd92A4+sOOhOD0=
 =FRGg
 -----END PGP SIGNATURE-----

Merge tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma

Pull hmm updates from Jason Gunthorpe:
 "This is more cleanup and consolidation of the hmm APIs and the very
  strongly related mmu_notifier interfaces. Many places across the tree
  using these interfaces are touched in the process. Beyond that a
  cleanup to the page walker API and a few memremap related changes
  round out the series:

   - General improvement of hmm_range_fault() and related APIs, more
     documentation, bug fixes from testing, API simplification &
     consolidation, and unused API removal

   - Simplify the hmm related kconfigs to HMM_MIRROR and DEVICE_PRIVATE,
     and make them internal kconfig selects

   - Hoist a lot of code related to mmu notifier attachment out of
     drivers by using a refcount get/put attachment idiom and remove the
     convoluted mmu_notifier_unregister_no_release() and related APIs.

   - General API improvement for the migrate_vma API and revision of its
     only user in nouveau

   - Annotate mmu_notifiers with lockdep and sleeping region debugging

  Two series unrelated to HMM or mmu_notifiers came along due to
  dependencies:

   - Allow pagemap's memremap_pages family of APIs to work without
     providing a struct device

   - Make walk_page_range() and related use a constant structure for
     function pointers"

* tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma: (75 commits)
  libnvdimm: Enable unit test infrastructure compile checks
  mm, notifier: Catch sleeping/blocking for !blockable
  kernel.h: Add non_block_start/end()
  drm/radeon: guard against calling an unpaired radeon_mn_unregister()
  csky: add missing brackets in a macro for tlb.h
  pagewalk: use lockdep_assert_held for locking validation
  pagewalk: separate function pointers from iterator data
  mm: split out a new pagewalk.h header from mm.h
  mm/mmu_notifiers: annotate with might_sleep()
  mm/mmu_notifiers: prime lockdep
  mm/mmu_notifiers: add a lockdep map for invalidate_range_start/end
  mm/mmu_notifiers: remove the __mmu_notifier_invalidate_range_start/end exports
  mm/hmm: hmm_range_fault() infinite loop
  mm/hmm: hmm_range_fault() NULL pointer bug
  mm/hmm: fix hmm_range_fault()'s handling of swapped out pages
  mm/mmu_notifiers: remove unregister_no_release
  RDMA/odp: remove ib_ucontext from ib_umem
  RDMA/odp: use mmu_notifier_get/put for 'struct ib_ucontext_per_mm'
  RDMA/mlx5: Use odp instead of mr->umem in pagefault_mr
  RDMA/mlx5: Use ib_umem_start instead of umem.address
  ...
 2019-09-21 10:07:42 -07:00
Linus Torvalds 77dcfe2b9e Power management updates for 5.4-rc1 
- Rework the main suspend-to-idle control flow to avoid repeating
    "noirq" device resume and suspend operations in case of spurious
    wakeups from the ACPI EC and decouple the ACPI EC wakeups support
    from the LPS0 _DSM support (Rafael Wysocki).
 
  - Extend the wakeup sources framework to expose wakeup sources as
    device objects in sysfs (Tri Vo, Stephen Boyd).
 
  - Expose system suspend statistics in sysfs (Kalesh Singh).
 
  - Introduce a new haltpoll cpuidle driver and a new matching
    governor for virtualized guests wanting to do guest-side polling
    in the idle loop (Marcelo Tosatti, Joao Martins, Wanpeng Li,
    Stephen Rothwell).
 
  - Fix the menu and teo cpuidle governors to allow the scheduler tick
    to be stopped if PM QoS is used to limit the CPU idle state exit
    latency in some cases (Rafael Wysocki).
 
  - Increase the resolution of the play_idle() argument to microseconds
    for more fine-grained injection of CPU idle cycles (Daniel Lezcano).
 
  - Switch over some users of cpuidle notifiers to the new QoS-based
    frequency limits and drop the CPUFREQ_ADJUST and CPUFREQ_NOTIFY
    policy notifier events (Viresh Kumar).
 
  - Add new cpufreq driver based on nvmem for sun50i (Yangtao Li).
 
  - Add support for MT8183 and MT8516 to the mediatek cpufreq driver
    (Andrew-sh.Cheng, Fabien Parent).
 
  - Add i.MX8MN support to the imx-cpufreq-dt cpufreq driver (Anson
    Huang).
 
  - Add qcs404 to cpufreq-dt-platdev blacklist (Jorge Ramirez-Ortiz).
 
  - Update the qcom cpufreq driver (among other things, to make it
    easier to extend and to use kryo cpufreq for other nvmem-based
    SoCs) and add qcs404 support to it  (Niklas Cassel, Douglas
    RAILLARD, Sibi Sankar, Sricharan R).
 
  - Fix assorted issues and make assorted minor improvements in the
    cpufreq code (Colin Ian King, Douglas RAILLARD, Florian Fainelli,
    Gustavo Silva, Hariprasad Kelam).
 
  - Add new devfreq driver for NVidia Tegra20 (Dmitry Osipenko, Arnd
    Bergmann).
 
  - Add new Exynos PPMU events to devfreq events and extend that
    mechanism (Lukasz Luba).
 
  - Fix and clean up the exynos-bus devfreq driver (Kamil Konieczny).
 
  - Improve devfreq documentation and governor code, fix spelling
    typos in devfreq (Ezequiel Garcia, Krzysztof Kozlowski, Leonard
    Crestez, MyungJoo Ham, Gaël PORTAY).
 
  - Add regulators enable and disable to the OPP (operating performance
    points) framework (Kamil Konieczny).
 
  - Update the OPP framework to support multiple opp-suspend properties
    (Anson Huang).
 
  - Fix assorted issues and make assorted minor improvements in the OPP
    code (Niklas Cassel, Viresh Kumar, Yue Hu).
 
  - Clean up the generic power domains (genpd) framework (Ulf Hansson).
 
  - Clean up assorted pieces of power management code and documentation
    (Akinobu Mita, Amit Kucheria, Chuhong Yuan).
 
  - Update the pm-graph tool to version 5.5 including multiple fixes
    and improvements (Todd Brandt).
 
  - Update the cpupower utility (Benjamin Weis, Geert Uytterhoeven,
    Sébastien Szymanski).
 -----BEGIN PGP SIGNATURE-----
 
 iQJGBAABCAAwFiEE4fcc61cGeeHD/fCwgsRv/nhiVHEFAl2ArZ4SHHJqd0Byand5
 c29ja2kubmV0AAoJEILEb/54YlRxgfYQAK80hs43vWQDmp7XKrN4pQe8+qYULAGO
 fBfrFl+NG9y/cnuqnt3NtA8MoyNsMMkMLkpkEDMfSbYqqH5ehEzX5+uGJWiWx8+Y
 oH5KU8MH7Tj/utYaalGzDt0AHfHZDIGC0NCUNQJVtE/4mOANFabwsCwscp4MrD5Q
 WjFN8U4BrsmWgJdZ/U9QIWcDZ0I+1etCF+rZG2yxSv31FMq2Zk/Qm4YyobqCvQFl
 TR9rxl08wqUmIYIz5cDjt/3AKH7NLLDqOTstbCL7cmufM5XPFc1yox69xc89UrIa
 4AMgmDp7SMwFG/gdUPof0WQNmx7qxmiRAPleAOYBOZW/8jPNZk2y+RhM5NeF72m7
 AFqYiuxqatkSb4IsT8fLzH9IUZOdYr8uSmoMQECw+MHdApaKFjFV8Lb/qx5+AwkD
 y7pwys8dZSamAjAf62eUzJDWcEwkNrujIisGrIXrVHb7ISbweskMOmdAYn9p4KgP
 dfRzpJBJ45IaMIdbaVXNpg3rP7Apfs7X1X+/ZhG6f+zHH3zYwr8Y81WPqX8WaZJ4
 qoVCyxiVWzMYjY2/1lzjaAdqWojPWHQ3or3eBaK52DouyG3jY6hCDTLwU7iuqcCX
 jzAtrnqrNIKufvaObEmqcmYlIIOFT7QaJCtGUSRFQLfSon8fsVSR7LLeXoAMUJKT
 JWQenuNaJngK
 =TBDQ
 -----END PGP SIGNATURE-----

Merge tag 'pm-5.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull power management updates from Rafael Wysocki:
 "These include a rework of the main suspend-to-idle code flow (related
  to the handling of spurious wakeups), a switch over of several users
  of cpufreq notifiers to QoS-based limits, a new devfreq driver for
  Tegra20, a new cpuidle driver and governor for virtualized guests, an
  extension of the wakeup sources framework to expose wakeup sources as
  device objects in sysfs, and more.

  Specifics:

   - Rework the main suspend-to-idle control flow to avoid repeating
     "noirq" device resume and suspend operations in case of spurious
     wakeups from the ACPI EC and decouple the ACPI EC wakeups support
     from the LPS0 _DSM support (Rafael Wysocki).

   - Extend the wakeup sources framework to expose wakeup sources as
     device objects in sysfs (Tri Vo, Stephen Boyd).

   - Expose system suspend statistics in sysfs (Kalesh Singh).

   - Introduce a new haltpoll cpuidle driver and a new matching governor
     for virtualized guests wanting to do guest-side polling in the idle
     loop (Marcelo Tosatti, Joao Martins, Wanpeng Li, Stephen Rothwell).

   - Fix the menu and teo cpuidle governors to allow the scheduler tick
     to be stopped if PM QoS is used to limit the CPU idle state exit
     latency in some cases (Rafael Wysocki).

   - Increase the resolution of the play_idle() argument to microseconds
     for more fine-grained injection of CPU idle cycles (Daniel
     Lezcano).

   - Switch over some users of cpuidle notifiers to the new QoS-based
     frequency limits and drop the CPUFREQ_ADJUST and CPUFREQ_NOTIFY
     policy notifier events (Viresh Kumar).

   - Add new cpufreq driver based on nvmem for sun50i (Yangtao Li).

   - Add support for MT8183 and MT8516 to the mediatek cpufreq driver
     (Andrew-sh.Cheng, Fabien Parent).

   - Add i.MX8MN support to the imx-cpufreq-dt cpufreq driver (Anson
     Huang).

   - Add qcs404 to cpufreq-dt-platdev blacklist (Jorge Ramirez-Ortiz).

   - Update the qcom cpufreq driver (among other things, to make it
     easier to extend and to use kryo cpufreq for other nvmem-based
     SoCs) and add qcs404 support to it (Niklas Cassel, Douglas
     RAILLARD, Sibi Sankar, Sricharan R).

   - Fix assorted issues and make assorted minor improvements in the
     cpufreq code (Colin Ian King, Douglas RAILLARD, Florian Fainelli,
     Gustavo Silva, Hariprasad Kelam).

   - Add new devfreq driver for NVidia Tegra20 (Dmitry Osipenko, Arnd
     Bergmann).

   - Add new Exynos PPMU events to devfreq events and extend that
     mechanism (Lukasz Luba).

   - Fix and clean up the exynos-bus devfreq driver (Kamil Konieczny).

   - Improve devfreq documentation and governor code, fix spelling typos
     in devfreq (Ezequiel Garcia, Krzysztof Kozlowski, Leonard Crestez,
     MyungJoo Ham, Gaël PORTAY).

   - Add regulators enable and disable to the OPP (operating performance
     points) framework (Kamil Konieczny).

   - Update the OPP framework to support multiple opp-suspend properties
     (Anson Huang).

   - Fix assorted issues and make assorted minor improvements in the OPP
     code (Niklas Cassel, Viresh Kumar, Yue Hu).

   - Clean up the generic power domains (genpd) framework (Ulf Hansson).

   - Clean up assorted pieces of power management code and documentation
     (Akinobu Mita, Amit Kucheria, Chuhong Yuan).

   - Update the pm-graph tool to version 5.5 including multiple fixes
     and improvements (Todd Brandt).

   - Update the cpupower utility (Benjamin Weis, Geert Uytterhoeven,
     Sébastien Szymanski)"

* tag 'pm-5.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (126 commits)
  cpuidle-haltpoll: Enable kvm guest polling when dedicated physical CPUs are available
  cpuidle-haltpoll: do not set an owner to allow modunload
  cpuidle-haltpoll: return -ENODEV on modinit failure
  cpuidle-haltpoll: set haltpoll as preferred governor
  cpuidle: allow governor switch on cpuidle_register_driver()
  PM: runtime: Documentation: add runtime_status ABI document
  pm-graph: make setVal unbuffered again for python2 and python3
  powercap: idle_inject: Use higher resolution for idle injection
  cpuidle: play_idle: Increase the resolution to usec
  cpuidle-haltpoll: vcpu hotplug support
  cpufreq: Add qcs404 to cpufreq-dt-platdev blacklist
  cpufreq: qcom: Add support for qcs404 on nvmem driver
  cpufreq: qcom: Refactor the driver to make it easier to extend
  cpufreq: qcom: Re-organise kryo cpufreq to use it for other nvmem based qcom socs
  dt-bindings: opp: Add qcom-opp bindings with properties needed for CPR
  dt-bindings: opp: qcom-nvmem: Support pstates provided by a power domain
  Documentation: cpufreq: Update policy notifier documentation
  cpufreq: Remove CPUFREQ_ADJUST and CPUFREQ_NOTIFY policy notifier events
  PM / Domains: Verify PM domain type in dev_pm_genpd_set_performance_state()
  PM / Domains: Simplify genpd_lookup_dev()
  ...
 2019-09-17 19:15:14 -07:00
Linus Torvalds 7f2444d38f Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 
Pull core timer updates from Thomas Gleixner:
 "Timers and timekeeping updates:

   - A large overhaul of the posix CPU timer code which is a preparation
     for moving the CPU timer expiry out into task work so it can be
     properly accounted on the task/process.

     An update to the bogus permission checks will come later during the
     merge window as feedback was not complete before heading of for
     travel.

   - Switch the timerqueue code to use cached rbtrees and get rid of the
     homebrewn caching of the leftmost node.

   - Consolidate hrtimer_init() + hrtimer_init_sleeper() calls into a
     single function

   - Implement the separation of hrtimers to be forced to expire in hard
     interrupt context even when PREEMPT_RT is enabled and mark the
     affected timers accordingly.

   - Implement a mechanism for hrtimers and the timer wheel to protect
     RT against priority inversion and live lock issues when a (hr)timer
     which should be canceled is currently executing the callback.
     Instead of infinitely spinning, the task which tries to cancel the
     timer blocks on a per cpu base expiry lock which is held and
     released by the (hr)timer expiry code.

   - Enable the Hyper-V TSC page based sched_clock for Hyper-V guests
     resulting in faster access to timekeeping functions.

   - Updates to various clocksource/clockevent drivers and their device
     tree bindings.

   - The usual small improvements all over the place"

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (101 commits)
  posix-cpu-timers: Fix permission check regression
  posix-cpu-timers: Always clear head pointer on dequeue
  hrtimer: Add a missing bracket and hide `migration_base' on !SMP
  posix-cpu-timers: Make expiry_active check actually work correctly
  posix-timers: Unbreak CONFIG_POSIX_TIMERS=n build
  tick: Mark sched_timer to expire in hard interrupt context
  hrtimer: Add kernel doc annotation for HRTIMER_MODE_HARD
  x86/hyperv: Hide pv_ops access for CONFIG_PARAVIRT=n
  posix-cpu-timers: Utilize timerqueue for storage
  posix-cpu-timers: Move state tracking to struct posix_cputimers
  posix-cpu-timers: Deduplicate rlimit handling
  posix-cpu-timers: Remove pointless comparisons
  posix-cpu-timers: Get rid of 64bit divisions
  posix-cpu-timers: Consolidate timer expiry further
  posix-cpu-timers: Get rid of zero checks
  rlimit: Rewrite non-sensical RLIMIT_CPU comment
  posix-cpu-timers: Respect INFINITY for hard RTTIME limit
  posix-cpu-timers: Switch thread group sampling to array
  posix-cpu-timers: Restructure expiry array
  posix-cpu-timers: Remove cputime_expires
  ...
 2019-09-17 12:35:15 -07:00
Qian Cai dac9f027b1 sched/fair: Remove unused cfs_rq_clock_task() function 
cfs_rq_clock_task() was first introduced and used in:

  f1b17280ef ("sched: Maintain runnable averages across throttled periods")

Over time its use has been graduately removed by the following commits:

  d31b1a66cb ("sched/fair: Factorize PELT update")
  2312729688 ("sched/fair: Update scale invariance of PELT")

Today, there is no single user left, so it can be safely removed.

Found via the -Wunused-function build warning.

Signed-off-by: Qian Cai <cai@lca.pw>
Cc: Ben Segall <bsegall@google.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/1568668775-2127-1-git-send-email-cai@lca.pw
[ Rewrote the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-17 09:55:02 +02:00
Rafael J. Wysocki ca61a72ac3 Merge branch 'pm-cpufreq' 
* pm-cpufreq: (36 commits)
  cpufreq: Add qcs404 to cpufreq-dt-platdev blacklist
  cpufreq: qcom: Add support for qcs404 on nvmem driver
  cpufreq: qcom: Refactor the driver to make it easier to extend
  cpufreq: qcom: Re-organise kryo cpufreq to use it for other nvmem based qcom socs
  dt-bindings: opp: Add qcom-opp bindings with properties needed for CPR
  dt-bindings: opp: qcom-nvmem: Support pstates provided by a power domain
  Documentation: cpufreq: Update policy notifier documentation
  cpufreq: Remove CPUFREQ_ADJUST and CPUFREQ_NOTIFY policy notifier events
  sched/cpufreq: Align trace event behavior of fast switching
  ACPI: cpufreq: Switch to QoS requests instead of cpufreq notifier
  video: pxafb: Remove cpufreq policy notifier
  video: sa1100fb: Remove cpufreq policy notifier
  arch_topology: Use CPUFREQ_CREATE_POLICY instead of CPUFREQ_NOTIFY
  cpufreq: powerpc_cbe: Switch to QoS requests for freq limits
  cpufreq: powerpc: macintosh: Switch to QoS requests for freq limits
  cpufreq: Print driver name if cpufreq_suspend() fails
  cpufreq: mediatek: Add support for mt8183
  cpufreq: mediatek: change to regulator_get_optional
  cpufreq: imx-cpufreq-dt: Add i.MX8MN support
  cpufreq: Use imx-cpufreq-dt for i.MX8MN's speed grading
  ...
 2019-09-17 09:44:29 +02:00
Rafael J. Wysocki 2cdd5cc703 Merge branch 'pm-cpuidle' 
* pm-cpuidle:
  cpuidle-haltpoll: Enable kvm guest polling when dedicated physical CPUs are available
  cpuidle-haltpoll: do not set an owner to allow modunload
  cpuidle-haltpoll: return -ENODEV on modinit failure
  cpuidle-haltpoll: set haltpoll as preferred governor
  cpuidle: allow governor switch on cpuidle_register_driver()
  powercap: idle_inject: Use higher resolution for idle injection
  cpuidle: play_idle: Increase the resolution to usec
  cpuidle-haltpoll: vcpu hotplug support
  cpuidle: teo: Get rid of redundant check in teo_update()
  cpuidle: teo: Allow tick to be stopped if PM QoS is used
  cpuidle: menu: Allow tick to be stopped if PM QoS is used
  cpuidle: header file stubs must be "static inline"
  cpuidle-haltpoll: disable host side polling when kvm virtualized
  cpuidle: add haltpoll governor
  governors: unify last_state_idx
  cpuidle: add poll_limit_ns to cpuidle_device structure
  add cpuidle-haltpoll driver
 2019-09-17 09:41:26 +02:00
Linus Torvalds 7e67a85999 Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 
Pull scheduler updates from Ingo Molnar:

 - MAINTAINERS: Add Mark Rutland as perf submaintainer, Juri Lelli and
   Vincent Guittot as scheduler submaintainers. Add Dietmar Eggemann,
   Steven Rostedt, Ben Segall and Mel Gorman as scheduler reviewers.

   As perf and the scheduler is getting bigger and more complex,
   document the status quo of current responsibilities and interests,
   and spread the review pain^H^H^H^H fun via an increase in the Cc:
   linecount generated by scripts/get_maintainer.pl. :-)

 - Add another series of patches that brings the -rt (PREEMPT_RT) tree
   closer to mainline: split the monolithic CONFIG_PREEMPT dependencies
   into a new CONFIG_PREEMPTION category that will allow the eventual
   introduction of CONFIG_PREEMPT_RT. Still a few more hundred patches
   to go though.

 - Extend the CPU cgroup controller with uclamp.min and uclamp.max to
   allow the finer shaping of CPU bandwidth usage.

 - Micro-optimize energy-aware wake-ups from O(CPUS^2) to O(CPUS).

 - Improve the behavior of high CPU count, high thread count
   applications running under cpu.cfs_quota_us constraints.

 - Improve balancing with SCHED_IDLE (SCHED_BATCH) tasks present.

 - Improve CPU isolation housekeeping CPU allocation NUMA locality.

 - Fix deadline scheduler bandwidth calculations and logic when cpusets
   rebuilds the topology, or when it gets deadline-throttled while it's
   being offlined.

 - Convert the cpuset_mutex to percpu_rwsem, to allow it to be used from
   setscheduler() system calls without creating global serialization.
   Add new synchronization between cpuset topology-changing events and
   the deadline acceptance tests in setscheduler(), which were broken
   before.

 - Rework the active_mm state machine to be less confusing and more
   optimal.

 - Rework (simplify) the pick_next_task() slowpath.

 - Improve load-balancing on AMD EPYC systems.

 - ... and misc cleanups, smaller fixes and improvements - please see
   the Git log for more details.

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (53 commits)
  sched/psi: Correct overly pessimistic size calculation
  sched/fair: Speed-up energy-aware wake-ups
  sched/uclamp: Always use 'enum uclamp_id' for clamp_id values
  sched/uclamp: Update CPU's refcount on TG's clamp changes
  sched/uclamp: Use TG's clamps to restrict TASK's clamps
  sched/uclamp: Propagate system defaults to the root group
  sched/uclamp: Propagate parent clamps
  sched/uclamp: Extend CPU's cgroup controller
  sched/topology: Improve load balancing on AMD EPYC systems
  arch, ia64: Make NUMA select SMP
  sched, perf: MAINTAINERS update, add submaintainers and reviewers
  sched/fair: Use rq_lock/unlock in online_fair_sched_group
  cpufreq: schedutil: fix equation in comment
  sched: Rework pick_next_task() slow-path
  sched: Allow put_prev_task() to drop rq->lock
  sched/fair: Expose newidle_balance()
  sched: Add task_struct pointer to sched_class::set_curr_task
  sched: Rework CPU hotplug task selection
  sched/{rt,deadline}: Fix set_next_task vs pick_next_task
  sched: Fix kerneldoc comment for ia64_set_curr_task
  ...
 2019-09-16 17:25:49 -07:00
Linus Torvalds 94d18ee934 Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 
Pull RCU updates from Ingo Molnar:
 "This cycle's RCU changes were:

   - A few more RCU flavor consolidation cleanups.

   - Updates to RCU's list-traversal macros improving lockdep usability.

   - Forward-progress improvements for no-CBs CPUs: Avoid ignoring
     incoming callbacks during grace-period waits.

   - Forward-progress improvements for no-CBs CPUs: Use ->cblist
     structure to take advantage of others' grace periods.

   - Also added a small commit that avoids needlessly inflicting
     scheduler-clock ticks on callback-offloaded CPUs.

   - Forward-progress improvements for no-CBs CPUs: Reduce contention on
     ->nocb_lock guarding ->cblist.

   - Forward-progress improvements for no-CBs CPUs: Add ->nocb_bypass
     list to further reduce contention on ->nocb_lock guarding ->cblist.

   - Miscellaneous fixes.

   - Torture-test updates.

   - minor LKMM updates"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (86 commits)
  MAINTAINERS: Update from paulmck@linux.ibm.com to paulmck@kernel.org
  rcu: Don't include <linux/ktime.h> in rcutiny.h
  rcu: Allow rcu_do_batch() to dynamically adjust batch sizes
  rcu/nocb: Don't wake no-CBs GP kthread if timer posted under overload
  rcu/nocb: Reduce __call_rcu_nocb_wake() leaf rcu_node ->lock contention
  rcu/nocb: Reduce nocb_cb_wait() leaf rcu_node ->lock contention
  rcu/nocb: Advance CBs after merge in rcutree_migrate_callbacks()
  rcu/nocb: Avoid synchronous wakeup in __call_rcu_nocb_wake()
  rcu/nocb: Print no-CBs diagnostics when rcutorture writer unduly delayed
  rcu/nocb: EXP Check use and usefulness of ->nocb_lock_contended
  rcu/nocb: Add bypass callback queueing
  rcu/nocb: Atomic ->len field in rcu_segcblist structure
  rcu/nocb: Unconditionally advance and wake for excessive CBs
  rcu/nocb: Reduce ->nocb_lock contention with separate ->nocb_gp_lock
  rcu/nocb: Reduce contention at no-CBs invocation-done time
  rcu/nocb: Reduce contention at no-CBs registry-time CB advancement
  rcu/nocb: Round down for number of no-CBs grace-period kthreads
  rcu/nocb: Avoid ->nocb_lock capture by corresponding CPU
  rcu/nocb: Avoid needless wakeups of no-CBs grace-period kthread
  rcu/nocb: Make __call_rcu_nocb_wake() safe for many callbacks
  ...
 2019-09-16 16:28:19 -07:00
Ingo Molnar 563c4f85f9 Merge branch 'sched/rt' into sched/core, to pick up -rt changes 
Pick up the first couple of patches working towards PREEMPT_RT.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-16 14:05:04 +02:00
Miles Chen 4adcdcea71 sched/psi: Correct overly pessimistic size calculation 
When passing a equal or more then 32 bytes long string to psi_write(),
psi_write() copies 31 bytes to its buf and overwrites buf[30]
with '\0'. Which makes the input string 1 byte shorter than
it should be.

Fix it by copying sizeof(buf) bytes when nbytes >= sizeof(buf).

This does not cause problems in normal use case like:
"some 500000 10000000" or "full 500000 10000000" because they
are less than 32 bytes in length.

	/* assuming nbytes == 35 */
	char buf[32];

	buf_size = min(nbytes, (sizeof(buf) - 1)); /* buf_size = 31 */
	if (copy_from_user(buf, user_buf, buf_size))
		return -EFAULT;

	buf[buf_size - 1] = '\0'; /* buf[30] = '\0' */

Before:

 %cd /proc/pressure/
 %echo "123456789|123456789|123456789|1234" > memory
 [   22.473497] nbytes=35,buf_size=31
 [   22.473775] 123456789|123456789|123456789| (print 30 chars)
 %sh: write error: Invalid argument

 %echo "123456789|123456789|123456789|1" > memory
 [   64.916162] nbytes=32,buf_size=31
 [   64.916331] 123456789|123456789|123456789| (print 30 chars)
 %sh: write error: Invalid argument

After:

 %cd /proc/pressure/
 %echo "123456789|123456789|123456789|1234" > memory
 [  254.837863] nbytes=35,buf_size=32
 [  254.838541] 123456789|123456789|123456789|1 (print 31 chars)
 %sh: write error: Invalid argument

 %echo "123456789|123456789|123456789|1" > memory
 [ 9965.714935] nbytes=32,buf_size=32
 [ 9965.715096] 123456789|123456789|123456789|1 (print 31 chars)
 %sh: write error: Invalid argument

Also remove the superfluous parentheses.

Signed-off-by: Miles Chen <miles.chen@mediatek.com>
Cc: <linux-mediatek@lists.infradead.org>
Cc: <wsd_upstream@mediatek.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190912103452.13281-1-miles.chen@mediatek.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-13 07:49:28 +02:00
Quentin Perret eb92692b25 sched/fair: Speed-up energy-aware wake-ups 
EAS computes the energy impact of migrating a waking task when deciding
on which CPU it should run. However, the current approach is known to
have a high algorithmic complexity, which can result in prohibitively
high wake-up latencies on systems with complex energy models, such as
systems with per-CPU DVFS. On such systems, the algorithm complexity is
in O(n^2) (ignoring the cost of searching for performance states in the
EM) with 'n' the number of CPUs.

To address this, re-factor the EAS wake-up path to compute the energy
'delta' (with and without the task) on a per-performance domain basis,
rather than system-wide, which brings the complexity down to O(n).

No functional changes intended.

Test results
~~~~~~~~~~~~

* Setup: Tested on a Google Pixel 3, with a Snapdragon 845 (4+4 CPUs,
  A55/A75). Base kernel is 5.3-rc5 + Pixel3 specific patches. Android
  userspace, no graphics.

* Test case:  Run a periodic rt-app task, with 16ms period, ramping down
  from 70% to 10%, in 5% steps of 500 ms each (json avail. at [1]).
  Frequencies of all CPUs are pinned to max (using scaling_min_freq
  CPUFreq sysfs entries) to reduce variability. The time to run
  select_task_rq_fair() is measured using the function profiler
  (/sys/kernel/debug/tracing/trace_stat/function*). See the test script
  for more details [2].

Test 1:

I hacked the DT to 'fake' per-CPU DVFS. That is, we end up with one
CPUFreq policy per CPU (8 policies in total). Since all frequencies are
pinned to max for the test, this should have no impact on the actual
frequency selection, but it does in the EAS calculation.

      +---------------------------+----------------------------------+
      | Without patch             | With patch                       |
+-----+-----+----------+----------+-----+-----------------+----------+
| CPU | Hit | Avg (us) | s^2 (us) | Hit | Avg (us)        | s^2 (us) |
|-----+-----+----------+----------+-----+-----------------+----------+
|  0  | 274 | 38.303   | 1750.239 | 401 | 14.126 (-63.1%) | 146.625  |
|  1  | 197 | 49.529   | 1695.852 | 314 | 16.135 (-67.4%) | 167.525  |
|  2  | 142 | 34.296   | 1758.665 | 302 | 14.133 (-58.8%) | 130.071  |
|  3  | 172 | 31.734   | 1490.975 | 641 | 14.637 (-53.9%) | 139.189  |
|  4  | 316 | 7.834    | 178.217  | 425 | 5.413  (-30.9%) | 20.803   |
|  5  | 447 | 8.424    | 144.638  | 556 | 5.929  (-29.6%) | 27.301   |
|  6  | 581 | 14.886   | 346.793  | 456 | 5.711  (-61.6%) | 23.124   |
|  7  | 456 | 10.005   | 211.187  | 997 | 4.708  (-52.9%) | 21.144   |
+-----+-----+----------+----------+-----+-----------------+----------+
             * Hit, Avg and s^2 are as reported by the function profiler

Test 2:
I also ran the same test with a normal DT, with 2 CPUFreq policies, to
see if this causes regressions in the most common case.

      +---------------------------+----------------------------------+
      | Without patch             | With patch                       |
+-----+-----+----------+----------+-----+-----------------+----------+
| CPU | Hit | Avg (us) | s^2 (us) | Hit | Avg (us)        | s^2 (us) |
|-----+-----+----------+----------+-----+-----------------+----------+
|  0  | 345 | 22.184   | 215.321  | 580 | 18.635 (-16.0%) | 146.892  |
|  1  | 358 | 18.597   | 200.596  | 438 | 12.934 (-30.5%) | 104.604  |
|  2  | 359 | 25.566   | 200.217  | 397 | 10.826 (-57.7%) | 74.021   |
|  3  | 362 | 16.881   | 200.291  | 718 | 11.455 (-32.1%) | 102.280  |
|  4  | 457 | 3.822    | 9.895    | 757 | 4.616  (+20.8%) | 13.369   |
|  5  | 344 | 4.301    | 7.121    | 594 | 5.320  (+23.7%) | 18.798   |
|  6  | 472 | 4.326    | 7.849    | 464 | 5.648  (+30.6%) | 22.022   |
|  7  | 331 | 4.630    | 13.937   | 408 | 5.299  (+14.4%) | 18.273   |
+-----+-----+----------+----------+-----+-----------------+----------+
             * Hit, Avg and s^2 are as reported by the function profiler

In addition to these two tests, I also ran 50 iterations of the Lisa
EAS functional test suite [3] with this patch applied on Arm Juno r0,
Arm Juno r2, Arm TC2 and Hikey960, and could not see any regressions
(all EAS functional tests are passing).

 [1] https://paste.debian.net/1100055/
 [2] https://paste.debian.net/1100057/
 [3] https://github.com/ARM-software/lisa/blob/master/lisa/tests/scheduler/eas_behaviour.py

Signed-off-by: Quentin Perret <quentin.perret@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: juri.lelli@redhat.com
Cc: morten.rasmussen@arm.com
Cc: qais.yousef@arm.com
Cc: qperret@qperret.net
Cc: rjw@rjwysocki.net
Cc: tkjos@google.com
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Link: https://lkml.kernel.org/r/20190912094404.13802-1-qperret@qperret.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-13 07:45:17 +02:00
Daniel Vetter 312364f353 kernel.h: Add non_block_start/end() 
In some special cases we must not block, but there's not a spinlock,
preempt-off, irqs-off or similar critical section already that arms the
might_sleep() debug checks. Add a non_block_start/end() pair to annotate
these.

This will be used in the oom paths of mmu-notifiers, where blocking is not
allowed to make sure there's forward progress. Quoting Michal:

"The notifier is called from quite a restricted context - oom_reaper -
which shouldn't depend on any locks or sleepable conditionals. The code
should be swift as well but we mostly do care about it to make a forward
progress. Checking for sleepable context is the best thing we could come
up with that would describe these demands at least partially."

Peter also asked whether we want to catch spinlocks on top, but Michal
said those are less of a problem because spinlocks can't have an indirect
dependency upon the page allocator and hence close the loop with the oom
reaper.

Suggested by Michal Hocko.

Link: https://lore.kernel.org/r/20190826201425.17547-4-daniel.vetter@ffwll.ch
Acked-by: Christian König <christian.koenig@amd.com> (v1)
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
 2019-09-07 04:28:05 -03:00
Ingo Molnar 1251201c0d sched/core: Fix uclamp ABI bug, clean up and robustify sched_read_attr() ABI logic and code 
Thadeu Lima de Souza Cascardo reported that 'chrt' broke on recent kernels:

  $ chrt -p $$
  chrt: failed to get pid 26306's policy: Argument list too long

and he has root-caused the bug to the following commit increasing sched_attr
size and breaking sched_read_attr() into returning -EFBIG:

  a509a7cd79 ("sched/uclamp: Extend sched_setattr() to support utilization clamping")

The other, bigger bug is that the whole sched_getattr() and sched_read_attr()
logic of checking non-zero bits in new ABI components is arguably broken,
and pretty much any extension of the ABI will spuriously break the ABI.
That's way too fragile.

Instead implement the perf syscall's extensible ABI instead, which we
already implement on the sched_setattr() side:

 - if user-attributes have the same size as kernel attributes then the
   logic is unchanged.

 - if user-attributes are larger than the kernel knows about then simply
   skip the extra bits, but set attr->size to the (smaller) kernel size
   so that tooling can (in principle) handle older kernel as well.

 - if user-attributes are smaller than the kernel knows about then just
   copy whatever user-space can accept.

Also clean up the whole logic:

 - Simplify the code flow - there's no need for 'ret' for example.

 - Standardize on 'kattr/uattr' and 'ksize/usize' naming to make sure we
   always know which side we are dealing with.

 - Why is it called 'read' when what it does is to copy to user? This
   code is so far away from VFS read() semantics that the naming is
   actively confusing. Name it sched_attr_copy_to_user() instead, which
   mirrors other copy_to_user() functionality.

 - Move the attr->size assignment from the head of sched_getattr() to the
   sched_attr_copy_to_user() function. Nothing else within the kernel
   should care about the size of the structure.

With these fixes the sched_getattr() syscall now nicely supports an
extensible ABI in both a forward and backward compatible fashion, and
will also fix the chrt bug.

As an added bonus the bogus -EFBIG return is removed as well, which as
Thadeu noted should have been -E2BIG to begin with.

Reported-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Acked-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: a509a7cd79 ("sched/uclamp: Extend sched_setattr() to support utilization clamping")
Link: https://lkml.kernel.org/r/20190904075532.GA26751@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-04 19:51:30 +02:00
Daniel Lezcano 82e430a6df cpuidle: play_idle: Increase the resolution to usec 
The play_idle resolution is 1ms. The intel_powerclamp bases the idle
duration on jiffies. The idle injection API is also using msec based
duration but has no user yet.

Unfortunately, msec based time does not fit well when we want to
inject idle cycle precisely with shallow idle state.

In order to set the scene for the incoming idle injection user, move
the precision up to usec when calling play_idle.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
 2019-09-03 11:33:29 +02:00
Patrick Bellasi 0413d7f33e sched/uclamp: Always use 'enum uclamp_id' for clamp_id values 
The supported clamp indexes are defined in 'enum clamp_id', however, because
of the code logic in some of the first utilization clamping series version,
sometimes we needed to use 'unsigned int' to represent indices.

This is not more required since the final version of the uclamp_* APIs can
always use the proper enum uclamp_id type.

Fix it with a bulk rename now that we have all the bits merged.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Michal Koutny <mkoutny@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190822132811.31294-7-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-03 09:17:40 +02:00
Patrick Bellasi babbe170e0 sched/uclamp: Update CPU's refcount on TG's clamp changes 
On updates of task group (TG) clamp values, ensure that these new values
are enforced on all RUNNABLE tasks of the task group, i.e. all RUNNABLE
tasks are immediately boosted and/or capped as requested.

Do that each time we update effective clamps from cpu_util_update_eff().
Use the *cgroup_subsys_state (css) to walk the list of tasks in each
affected TG and update their RUNNABLE tasks.
Update each task by using the same mechanism used for cpu affinity masks
updates, i.e. by taking the rq lock.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Michal Koutny <mkoutny@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190822132811.31294-6-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-03 09:17:40 +02:00
Patrick Bellasi 3eac870a32 sched/uclamp: Use TG's clamps to restrict TASK's clamps 
When a task specific clamp value is configured via sched_setattr(2), this
value is accounted in the corresponding clamp bucket every time the task is
{en,de}qeued. However, when cgroups are also in use, the task specific
clamp values could be restricted by the task_group (TG) clamp values.

Update uclamp_cpu_inc() to aggregate task and TG clamp values. Every time a
task is enqueued, it's accounted in the clamp bucket tracking the smaller
clamp between the task specific value and its TG effective value. This
allows to:

1. ensure cgroup clamps are always used to restrict task specific requests,
   i.e. boosted not more than its TG effective protection and capped at
   least as its TG effective limit.

2. implement a "nice-like" policy, where tasks are still allowed to request
   less than what enforced by their TG effective limits and protections

Do this by exploiting the concept of "effective" clamp, which is already
used by a TG to track parent enforced restrictions.

Apply task group clamp restrictions only to tasks belonging to a child
group. While, for tasks in the root group or in an autogroup, system
defaults are still enforced.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Michal Koutny <mkoutny@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190822132811.31294-5-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-03 09:17:39 +02:00
Patrick Bellasi 7274a5c1bb sched/uclamp: Propagate system defaults to the root group 
The clamp values are not tunable at the level of the root task group.
That's for two main reasons:

 - the root group represents "system resources" which are always
   entirely available from the cgroup standpoint.

 - when tuning/restricting "system resources" makes sense, tuning must
   be done using a system wide API which should also be available when
   control groups are not.

When a system wide restriction is available, cgroups should be aware of
its value in order to know exactly how much "system resources" are
available for the subgroups.

Utilization clamping supports already the concepts of:

 - system defaults: which define the maximum possible clamp values
   usable by tasks.

 - effective clamps: which allows a parent cgroup to constraint (maybe
   temporarily) its descendants without losing the information related
   to the values "requested" from them.

Exploit these two concepts and bind them together in such a way that,
whenever system default are tuned, the new values are propagated to
(possibly) restrict or relax the "effective" value of nested cgroups.

When cgroups are in use, force an update of all the RUNNABLE tasks.
Otherwise, keep things simple and do just a lazy update next time each
task will be enqueued.
Do that since we assume a more strict resource control is required when
cgroups are in use. This allows also to keep "effective" clamp values
updated in case we need to expose them to user-space.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Michal Koutny <mkoutny@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190822132811.31294-4-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-03 09:17:38 +02:00
Patrick Bellasi 0b60ba2dd3 sched/uclamp: Propagate parent clamps 
In order to properly support hierarchical resources control, the cgroup
delegation model requires that attribute writes from a child group never
fail but still are locally consistent and constrained based on parent's
assigned resources. This requires to properly propagate and aggregate
parent attributes down to its descendants.

Implement this mechanism by adding a new "effective" clamp value for each
task group. The effective clamp value is defined as the smaller value
between the clamp value of a group and the effective clamp value of its
parent. This is the actual clamp value enforced on tasks in a task group.

Since it's possible for a cpu.uclamp.min value to be bigger than the
cpu.uclamp.max value, ensure local consistency by restricting each
"protection" (i.e. min utilization) with the corresponding "limit"
(i.e. max utilization).

Do that at effective clamps propagation to ensure all user-space write
never fails while still always tracking the most restrictive values.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Michal Koutny <mkoutny@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190822132811.31294-3-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-03 09:17:38 +02:00
Patrick Bellasi 2480c09313 sched/uclamp: Extend CPU's cgroup controller 
The cgroup CPU bandwidth controller allows to assign a specified
(maximum) bandwidth to the tasks of a group. However this bandwidth is
defined and enforced only on a temporal base, without considering the
actual frequency a CPU is running on. Thus, the amount of computation
completed by a task within an allocated bandwidth can be very different
depending on the actual frequency the CPU is running that task.
The amount of computation can be affected also by the specific CPU a
task is running on, especially when running on asymmetric capacity
systems like Arm's big.LITTLE.

With the availability of schedutil, the scheduler is now able
to drive frequency selections based on actual task utilization.
Moreover, the utilization clamping support provides a mechanism to
bias the frequency selection operated by schedutil depending on
constraints assigned to the tasks currently RUNNABLE on a CPU.

Giving the mechanisms described above, it is now possible to extend the
cpu controller to specify the minimum (or maximum) utilization which
should be considered for tasks RUNNABLE on a cpu.
This makes it possible to better defined the actual computational
power assigned to task groups, thus improving the cgroup CPU bandwidth
controller which is currently based just on time constraints.

Extend the CPU controller with a couple of new attributes uclamp.{min,max}
which allow to enforce utilization boosting and capping for all the
tasks in a group.

Specifically:

- uclamp.min: defines the minimum utilization which should be considered
	      i.e. the RUNNABLE tasks of this group will run at least at a
	      minimum frequency which corresponds to the uclamp.min
	      utilization

- uclamp.max: defines the maximum utilization which should be considered
	      i.e. the RUNNABLE tasks of this group will run up to a
	      maximum frequency which corresponds to the uclamp.max
	      utilization

These attributes:

a) are available only for non-root nodes, both on default and legacy
   hierarchies, while system wide clamps are defined by a generic
   interface which does not depends on cgroups. This system wide
   interface enforces constraints on tasks in the root node.

b) enforce effective constraints at each level of the hierarchy which
   are a restriction of the group requests considering its parent's
   effective constraints. Root group effective constraints are defined
   by the system wide interface.
   This mechanism allows each (non-root) level of the hierarchy to:
   - request whatever clamp values it would like to get
   - effectively get only up to the maximum amount allowed by its parent

c) have higher priority than task-specific clamps, defined via
   sched_setattr(), thus allowing to control and restrict task requests.

Add two new attributes to the cpu controller to collect "requested"
clamp values. Allow that at each non-root level of the hierarchy.
Keep it simple by not caring now about "effective" values computation
and propagation along the hierarchy.

Update sysctl_sched_uclamp_handler() to use the newly introduced
uclamp_mutex so that we serialize system default updates with cgroup
relate updates.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Michal Koutny <mkoutny@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190822132811.31294-2-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-03 09:17:37 +02:00
Matt Fleming a55c7454a8 sched/topology: Improve load balancing on AMD EPYC systems 
SD_BALANCE_{FORK,EXEC} and SD_WAKE_AFFINE are stripped in sd_init()
for any sched domains with a NUMA distance greater than 2 hops
(RECLAIM_DISTANCE). The idea being that it's expensive to balance
across domains that far apart.

However, as is rather unfortunately explained in:

  commit 32e45ff43e ("mm: increase RECLAIM_DISTANCE to 30")

the value for RECLAIM_DISTANCE is based on node distance tables from
2011-era hardware.

Current AMD EPYC machines have the following NUMA node distances:

 node distances:
 node   0   1   2   3   4   5   6   7
   0:  10  16  16  16  32  32  32  32
   1:  16  10  16  16  32  32  32  32
   2:  16  16  10  16  32  32  32  32
   3:  16  16  16  10  32  32  32  32
   4:  32  32  32  32  10  16  16  16
   5:  32  32  32  32  16  10  16  16
   6:  32  32  32  32  16  16  10  16
   7:  32  32  32  32  16  16  16  10

where 2 hops is 32.

The result is that the scheduler fails to load balance properly across
NUMA nodes on different sockets -- 2 hops apart.

For example, pinning 16 busy threads to NUMA nodes 0 (CPUs 0-7) and 4
(CPUs 32-39) like so,

  $ numactl -C 0-7,32-39 ./spinner 16

causes all threads to fork and remain on node 0 until the active
balancer kicks in after a few seconds and forcibly moves some threads
to node 4.

Override node_reclaim_distance for AMD Zen.

Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Suravee.Suthikulpanit@amd.com
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas.Lendacky@amd.com
Cc: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20190808195301.13222-3-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-03 09:17:37 +02:00
Liangyan 5e2d2cc258 sched/fair: Don't assign runtime for throttled cfs_rq 
do_sched_cfs_period_timer() will refill cfs_b runtime and call
distribute_cfs_runtime to unthrottle cfs_rq, sometimes cfs_b->runtime
will allocate all quota to one cfs_rq incorrectly, then other cfs_rqs
attached to this cfs_b can't get runtime and will be throttled.

We find that one throttled cfs_rq has non-negative
cfs_rq->runtime_remaining and cause an unexpetced cast from s64 to u64
in snippet:

  distribute_cfs_runtime() {
    runtime = -cfs_rq->runtime_remaining + 1;
  }

The runtime here will change to a large number and consume all
cfs_b->runtime in this cfs_b period.

According to Ben Segall, the throttled cfs_rq can have
account_cfs_rq_runtime called on it because it is throttled before
idle_balance, and the idle_balance calls update_rq_clock to add time
that is accounted to the task.

This commit prevents cfs_rq to be assgined new runtime if it has been
throttled until that distribute_cfs_runtime is called.

Signed-off-by: Liangyan <liangyan.peng@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Reviewed-by: Ben Segall <bsegall@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: shanpeic@linux.alibaba.com
Cc: stable@vger.kernel.org
Cc: xlpang@linux.alibaba.com
Fixes: d3d9dc3302 ("sched: Throttle entities exceeding their allowed bandwidth")
Link: https://lkml.kernel.org/r/20190826121633.6538-1-liangyan.peng@linux.alibaba.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-09-03 08:55:07 +02:00
Thomas Gleixner 3a245c0f11 posix-cpu-timers: Move expiry cache into struct posix_cputimers 
The expiry cache belongs into the posix_cputimers container where the other
cpu timers information is.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lkml.kernel.org/r/20190821192921.014444012@linutronix.de
 2019-08-28 11:50:35 +02:00
Douglas RAILLARD 77c84dd188 sched/cpufreq: Align trace event behavior of fast switching 
Fast switching path only emits an event for the CPU of interest, whereas the
regular path emits an event for all the CPUs that had their frequency changed,
i.e. all the CPUs sharing the same policy.

With the current behavior, looking at cpu_frequency event for a given CPU that
is using the fast switching path will not give the correct frequency signal.

Signed-off-by: Douglas RAILLARD <douglas.raillard@arm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
 2019-08-28 11:26:46 +02:00
Linus Torvalds 8a04c2ee62 Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 
Pull scheduler fix from Thomas Gleixner:
 "Handle the worker management in situations where a task is scheduled
  out on a PI lock contention correctly and schedule a new worker if
  possible"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/core: Schedule new worker even if PI-blocked
 2019-08-25 10:06:12 -07:00
Jason Xing 7b2b55da1d psi: get poll_work to run when calling poll syscall next time 
Only when calling the poll syscall the first time can user receive
POLLPRI correctly.  After that, user always fails to acquire the event
signal.

Reproduce case:
 1. Get the monitor code in Documentation/accounting/psi.txt
 2. Run it, and wait for the event triggered.
 3. Kill and restart the process.

The question is why we can end up with poll_scheduled = 1 but the work
not running (which would reset it to 0).  And the answer is because the
scheduling side sees group->poll_kworker under RCU protection and then
schedules it, but here we cancel the work and destroy the worker.  The
cancel needs to pair with resetting the poll_scheduled flag.

Link: http://lkml.kernel.org/r/1566357985-97781-1-git-send-email-joseph.qi@linux.alibaba.com
Signed-off-by: Jason Xing <kerneljasonxing@linux.alibaba.com>
Signed-off-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: Caspar Zhang <caspar@linux.alibaba.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-08-24 19:48:42 -07:00
Ingo Molnar 6c06b66e95 Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu 
Pull RCU and LKMM changes from Paul E. McKenney:

 - A few more RCU flavor consolidation cleanups.

 - Miscellaneous fixes.

 - Updates to RCU's list-traversal macros improving lockdep usability.

 - Torture-test updates.

 - Forward-progress improvements for no-CBs CPUs: Avoid ignoring
   incoming callbacks during grace-period waits.

 - Forward-progress improvements for no-CBs CPUs: Use ->cblist
   structure to take advantage of others' grace periods.

 - Also added a small commit that avoids needlessly inflicting
   scheduler-clock ticks on callback-offloaded CPUs.

 - Forward-progress improvements for no-CBs CPUs: Reduce contention
   on ->nocb_lock guarding ->cblist.

 - Forward-progress improvements for no-CBs CPUs: Add ->nocb_bypass
   list to further reduce contention on ->nocb_lock guarding ->cblist.

 - LKMM updates.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-08-22 20:52:04 +02:00
Sebastian Andrzej Siewior b0fdc01354 sched/core: Schedule new worker even if PI-blocked 
If a task is PI-blocked (blocking on sleeping spinlock) then we don't want to
schedule a new kworker if we schedule out due to lock contention because !RT
does not do that as well. A spinning spinlock disables preemption and a worker
does not schedule out on lock contention (but spin).

On RT the RW-semaphore implementation uses an rtmutex so
tsk_is_pi_blocked() will return true if a task blocks on it. In this case we
will now start a new worker which may deadlock if one worker is waiting on
progress from another worker. Since a RW-semaphore starts a new worker on !RT,
we should do the same on RT.

XFS is able to trigger this deadlock.

Allow to schedule new worker if the current worker is PI-blocked.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20190816160626.12742-1-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-08-19 10:57:26 +02:00
Rafael J. Wysocki a3ee2477c4 Merge branch 'pm-cpufreq' 
* pm-cpufreq:
  cpufreq: schedutil: Don't skip freq update when limits change
  cpufreq: dev_pm_qos_update_request() can return 1 on success
 2019-08-16 14:24:51 +02:00
Peter Zijlstra e78a7614f3 idle: Prevent late-arriving interrupts from disrupting offline 
Scheduling-clock interrupts can arrive late in the CPU-offline process,
after idle entry and the subsequent call to cpuhp_report_idle_dead().
Once execution passes the call to rcu_report_dead(), RCU is ignoring
the CPU, which results in lockdep complaints when the interrupt handler
uses RCU:

------------------------------------------------------------------------

=============================
WARNING: suspicious RCU usage
5.2.0-rc1+ #681 Not tainted
-----------------------------
kernel/sched/fair.c:9542 suspicious rcu_dereference_check() usage!

other info that might help us debug this:

RCU used illegally from offline CPU!
rcu_scheduler_active = 2, debug_locks = 1
no locks held by swapper/5/0.

stack backtrace:
CPU: 5 PID: 0 Comm: swapper/5 Not tainted 5.2.0-rc1+ #681
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS Bochs 01/01/2011
Call Trace:
 <IRQ>
 dump_stack+0x5e/0x8b
 trigger_load_balance+0xa8/0x390
 ? tick_sched_do_timer+0x60/0x60
 update_process_times+0x3b/0x50
 tick_sched_handle+0x2f/0x40
 tick_sched_timer+0x32/0x70
 __hrtimer_run_queues+0xd3/0x3b0
 hrtimer_interrupt+0x11d/0x270
 ? sched_clock_local+0xc/0x74
 smp_apic_timer_interrupt+0x79/0x200
 apic_timer_interrupt+0xf/0x20
 </IRQ>
RIP: 0010:delay_tsc+0x22/0x50
Code: ff 0f 1f 80 00 00 00 00 65 44 8b 05 18 a7 11 48 0f ae e8 0f 31 48 89 d6 48 c1 e6 20 48 09 c6 eb 0e f3 90 65 8b 05 fe a6 11 48 <41> 39 c0 75 18 0f ae e8 0f 31 48 c1 e2 20 48 09 c2 48 89 d0 48 29
RSP: 0000:ffff8f92c0157ed0 EFLAGS: 00000212 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000005 RBX: ffff8c861f356400 RCX: ffff8f92c0157e64
RDX: 000000321214c8cc RSI: 00000032120daa7f RDI: 0000000000260f15
RBP: 0000000000000005 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000000 R14: ffff8c861ee18000 R15: ffff8c861ee18000
 cpuhp_report_idle_dead+0x31/0x60
 do_idle+0x1d5/0x200
 ? _raw_spin_unlock_irqrestore+0x2d/0x40
 cpu_startup_entry+0x14/0x20
 start_secondary+0x151/0x170
 secondary_startup_64+0xa4/0xb0

------------------------------------------------------------------------

This happens rarely, but can be forced by happen more often by
placing delays in cpuhp_report_idle_dead() following the call to
rcu_report_dead().  With this in place, the following rcutorture
scenario reproduces the problem within a few minutes:

tools/testing/selftests/rcutorture/bin/kvm.sh --cpus 8 --duration 5 --kconfig "CONFIG_DEBUG_LOCK_ALLOC=y CONFIG_PROVE_LOCKING=y" --configs "TREE04"

This commit uses the crude but effective expedient of moving the disabling
of interrupts within the idle loop to precede the cpu_is_offline()
check.  It also invokes tick_nohz_idle_stop_tick() instead of
tick_nohz_idle_stop_tick_protected() to shut off the scheduling-clock
interrupt.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
[ paulmck: Revert tick_nohz_idle_stop_tick_protected() removal, new callers. ]
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
 2019-08-12 11:23:56 -07:00
Phil Auld a46d14eca7 sched/fair: Use rq_lock/unlock in online_fair_sched_group 
Enabling WARN_DOUBLE_CLOCK in /sys/kernel/debug/sched_features causes
warning to fire in update_rq_clock. This seems to be caused by onlining
a new fair sched group not using the rq lock wrappers.

  [] rq->clock_update_flags & RQCF_UPDATED
  [] WARNING: CPU: 5 PID: 54385 at kernel/sched/core.c:210 update_rq_clock+0xec/0x150

  [] Call Trace:
  []  online_fair_sched_group+0x53/0x100
  []  cpu_cgroup_css_online+0x16/0x20
  []  online_css+0x1c/0x60
  []  cgroup_apply_control_enable+0x231/0x3b0
  []  cgroup_mkdir+0x41b/0x530
  []  kernfs_iop_mkdir+0x61/0xa0
  []  vfs_mkdir+0x108/0x1a0
  []  do_mkdirat+0x77/0xe0
  []  do_syscall_64+0x55/0x1d0
  []  entry_SYSCALL_64_after_hwframe+0x44/0xa9

Using the wrappers in online_fair_sched_group instead of the raw locking
removes this warning.

[ tglx: Use rq_*lock_irq() ]

Signed-off-by: Phil Auld <pauld@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20190801133749.11033-1-pauld@redhat.com
 2019-08-12 14:45:34 +02:00
Viresh Kumar 600f5badb7 cpufreq: schedutil: Don't skip freq update when limits change 
To avoid reducing the frequency of a CPU prematurely, we skip reducing
the frequency if the CPU had been busy recently.

This should not be done when the limits of the policy are changed, for
example due to thermal throttling. We should always get the frequency
within the new limits as soon as possible.

Trying to fix this by using only one flag, i.e. need_freq_update, can
lead to a race condition where the flag gets cleared without forcing us
to change the frequency at least once. And so this patch introduces
another flag to avoid that race condition.

Fixes: ecd2884291 ("cpufreq: schedutil: Don't set next_freq to UINT_MAX")
Cc: v4.18+ <stable@vger.kernel.org> # v4.18+
Reported-by: Doug Smythies <dsmythies@telus.net>
Tested-by: Doug Smythies <dsmythies@telus.net>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
 2019-08-10 13:53:19 +02:00
Qais Yousef 5c3ceef9ad cpufreq: schedutil: fix equation in comment 
scale_irq_capacity() call in schedutil_cpu_util() does

	util *= (max - irq)
	util /= max

But the comment says

	util *= (1 - irq)
	util /= max

Fix the comment to match what the scaling function does.

Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "Rafael J . Wysocki" <rjw@rjwysocki.net>
Link: https://lkml.kernel.org/r/20190802104628.8410-1-qais.yousef@arm.com
 2019-08-08 09:09:31 +02:00
Peter Zijlstra 67692435c4 sched: Rework pick_next_task() slow-path 
Avoid the RETRY_TASK case in the pick_next_task() slow path.

By doing the put_prev_task() early, we get the rt/deadline pull done,
and by testing rq->nr_running we know if we need newidle_balance().

This then gives a stable state to pick a task from.

Since the fast-path is fair only; it means the other classes will
always have pick_next_task(.prev=NULL, .rf=NULL) and we can simplify.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Lu <aaron.lwe@gmail.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: mingo@kernel.org
Cc: Phil Auld <pauld@redhat.com>
Cc: Julien Desfossez <jdesfossez@digitalocean.com>
Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>
Link: https://lkml.kernel.org/r/aa34d24b36547139248f32a30138791ac6c02bd6.1559129225.git.vpillai@digitalocean.com
 2019-08-08 09:09:31 +02:00
Peter Zijlstra 5f2a45fc9e sched: Allow put_prev_task() to drop rq->lock 
Currently the pick_next_task() loop is convoluted and ugly because of
how it can drop the rq->lock and needs to restart the picking.

For the RT/Deadline classes, it is put_prev_task() where we do
balancing, and we could do this before the picking loop. Make this
possible.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Aaron Lu <aaron.lwe@gmail.com>
Cc: mingo@kernel.org
Cc: Phil Auld <pauld@redhat.com>
Cc: Julien Desfossez <jdesfossez@digitalocean.com>
Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>
Link: https://lkml.kernel.org/r/e4519f6850477ab7f3d257062796e6425ee4ba7c.1559129225.git.vpillai@digitalocean.com
 2019-08-08 09:09:31 +02:00
Peter Zijlstra 5ba553eff0 sched/fair: Expose newidle_balance() 
For pick_next_task_fair() it is the newidle balance that requires
dropping the rq->lock; provided we do put_prev_task() early, we can
also detect the condition for doing newidle early.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Lu <aaron.lwe@gmail.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: mingo@kernel.org
Cc: Phil Auld <pauld@redhat.com>
Cc: Julien Desfossez <jdesfossez@digitalocean.com>
Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>
Link: https://lkml.kernel.org/r/9e3eb1859b946f03d7e500453a885725b68957ba.1559129225.git.vpillai@digitalocean.com
 2019-08-08 09:09:31 +02:00
Peter Zijlstra 03b7fad167 sched: Add task_struct pointer to sched_class::set_curr_task 
In preparation of further separating pick_next_task() and
set_curr_task() we have to pass the actual task into it, while there,
rename the thing to better pair with put_prev_task().

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Lu <aaron.lwe@gmail.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: mingo@kernel.org
Cc: Phil Auld <pauld@redhat.com>
Cc: Julien Desfossez <jdesfossez@digitalocean.com>
Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>
Link: https://lkml.kernel.org/r/a96d1bcdd716db4a4c5da2fece647a1456c0ed78.1559129225.git.vpillai@digitalocean.com
 2019-08-08 09:09:31 +02:00
Peter Zijlstra 10e7071b2f sched: Rework CPU hotplug task selection 
The CPU hotplug task selection is the only place where we used
put_prev_task() on a task that is not current. While looking at that,
it occured to me that we can simplify all that by by using a custom
pick loop.

Since we don't need to put current, we can do away with the fake task
too.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Lu <aaron.lwe@gmail.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: mingo@kernel.org
Cc: Phil Auld <pauld@redhat.com>
Cc: Julien Desfossez <jdesfossez@digitalocean.com>
Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>
 2019-08-08 09:09:30 +02:00
Peter Zijlstra f95d4eaee6 sched/{rt,deadline}: Fix set_next_task vs pick_next_task 
Because pick_next_task() implies set_curr_task() and some of the
details haven't mattered too much, some of what _should_ be in
set_curr_task() ended up in pick_next_task, correct this.

This prepares the way for a pick_next_task() variant that does not
affect the current state; allowing remote picking.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Lu <aaron.lwe@gmail.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: mingo@kernel.org
Cc: Phil Auld <pauld@redhat.com>
Cc: Julien Desfossez <jdesfossez@digitalocean.com>
Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>
Link: https://lkml.kernel.org/r/38c61d5240553e043c27c5e00b9dd0d184dd6081.1559129225.git.vpillai@digitalocean.com
 2019-08-08 09:09:30 +02:00
Peter Zijlstra 5feeb7837a sched: Fix kerneldoc comment for ia64_set_curr_task 
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Lu <aaron.lwe@gmail.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: mingo@kernel.org
Cc: Phil Auld <pauld@redhat.com>
Cc: Julien Desfossez <jdesfossez@digitalocean.com>
Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>
Link: https://lkml.kernel.org/r/fde3a65ea3091ec6b84dac3c19639f85f452c5d1.1559129225.git.vpillai@digitalocean.com
 2019-08-08 09:09:30 +02:00
Dave Chiluk de53fd7aed sched/fair: Fix low cpu usage with high throttling by removing expiration of cpu-local slices 
It has been observed, that highly-threaded, non-cpu-bound applications
running under cpu.cfs_quota_us constraints can hit a high percentage of
periods throttled while simultaneously not consuming the allocated
amount of quota. This use case is typical of user-interactive non-cpu
bound applications, such as those running in kubernetes or mesos when
run on multiple cpu cores.

This has been root caused to cpu-local run queue being allocated per cpu
bandwidth slices, and then not fully using that slice within the period.
At which point the slice and quota expires. This expiration of unused
slice results in applications not being able to utilize the quota for
which they are allocated.

The non-expiration of per-cpu slices was recently fixed by
'commit 512ac999d2 ("sched/fair: Fix bandwidth timer clock drift
condition")'. Prior to that it appears that this had been broken since
at least 'commit 51f2176d74 ("sched/fair: Fix unlocked reads of some
cfs_b->quota/period")' which was introduced in v3.16-rc1 in 2014. That
added the following conditional which resulted in slices never being
expired.

if (cfs_rq->runtime_expires != cfs_b->runtime_expires) {
	/* extend local deadline, drift is bounded above by 2 ticks */
	cfs_rq->runtime_expires += TICK_NSEC;

Because this was broken for nearly 5 years, and has recently been fixed
and is now being noticed by many users running kubernetes
(https://github.com/kubernetes/kubernetes/issues/67577) it is my opinion
that the mechanisms around expiring runtime should be removed
altogether.

This allows quota already allocated to per-cpu run-queues to live longer
than the period boundary. This allows threads on runqueues that do not
use much CPU to continue to use their remaining slice over a longer
period of time than cpu.cfs_period_us. However, this helps prevent the
above condition of hitting throttling while also not fully utilizing
your cpu quota.

This theoretically allows a machine to use slightly more than its
allotted quota in some periods. This overflow would be bounded by the
remaining quota left on each per-cpu runqueueu. This is typically no
more than min_cfs_rq_runtime=1ms per cpu. For CPU bound tasks this will
change nothing, as they should theoretically fully utilize all of their
quota in each period. For user-interactive tasks as described above this
provides a much better user/application experience as their cpu
utilization will more closely match the amount they requested when they
hit throttling. This means that cpu limits no longer strictly apply per
period for non-cpu bound applications, but that they are still accurate
over longer timeframes.

This greatly improves performance of high-thread-count, non-cpu bound
applications with low cfs_quota_us allocation on high-core-count
machines. In the case of an artificial testcase (10ms/100ms of quota on
80 CPU machine), this commit resulted in almost 30x performance
improvement, while still maintaining correct cpu quota restrictions.
That testcase is available at https://github.com/indeedeng/fibtest.

Fixes: 512ac999d2 ("sched/fair: Fix bandwidth timer clock drift condition")
Signed-off-by: Dave Chiluk <chiluk+linux@indeed.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Reviewed-by: Ben Segall <bsegall@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: John Hammond <jhammond@indeed.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kyle Anderson <kwa@yelp.com>
Cc: Gabriel Munos <gmunoz@netflix.com>
Cc: Peter Oskolkov <posk@posk.io>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Brendan Gregg <bgregg@netflix.com>
Link: https://lkml.kernel.org/r/1563900266-19734-2-git-send-email-chiluk+linux@indeed.com
 2019-08-08 09:09:30 +02:00
Peter Zijlstra 139d025cda sched: Clean up active_mm reference counting 
The current active_mm reference counting is confusing and sub-optimal.

Rewrite the code to explicitly consider the 4 separate cases:

    user -> user

	When switching between two user tasks, all we need to consider
	is switch_mm().

    user -> kernel

	When switching from a user task to a kernel task (which
	doesn't have an associated mm) we retain the last mm in our
	active_mm. Increment a reference count on active_mm.

  kernel -> kernel

	When switching between kernel threads, all we need to do is
	pass along the active_mm reference.

  kernel -> user

	When switching between a kernel and user task, we must switch
	from the last active_mm to the next mm, hoping of course that
	these are the same. Decrement a reference on the active_mm.

The code keeps a different order, because as you'll note, both 'to
user' cases require switch_mm().

And where the old code would increment/decrement for the 'kernel ->
kernel' case, the new code observes this is a neutral operation and
avoids touching the reference count.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: luto@kernel.org
 2019-08-08 09:09:30 +02:00
Suren Baghdasaryan 04e048cf09 sched/psi: Do not require setsched permission from the trigger creator 
When a process creates a new trigger by writing into /proc/pressure/*
files, permissions to write such a file should be used to determine whether
the process is allowed to do so or not. Current implementation would also
require such a process to have setsched capability. Setting of psi trigger
thread's scheduling policy is an implementation detail and should not be
exposed to the user level. Remove the permission check by using _nocheck
version of the function.

Suggested-by: Nick Kralevich <nnk@google.com>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: lizefan@huawei.com
Cc: mingo@redhat.com
Cc: akpm@linux-foundation.org
Cc: kernel-team@android.com
Cc: dennisszhou@gmail.com
Cc: dennis@kernel.org
Cc: hannes@cmpxchg.org
Cc: axboe@kernel.dk
Link: https://lkml.kernel.org/r/20190730013310.162367-1-surenb@google.com
 2019-08-06 12:49:18 +02:00
Peter Zijlstra 14f5c7b46a sched/psi: Reduce psimon FIFO priority 
PSI defaults to a FIFO-99 thread, reduce this to FIFO-1.

FIFO-99 is the very highest priority available to SCHED_FIFO and
it not a suitable default; it would indicate the psi work is the
most important work on the machine.

Since Real-Time tasks will have pre-allocated memory and locked it in
place, Real-Time tasks do not care about PSI. All it needs is to be
above OTHER.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
 2019-08-06 12:49:18 +02:00
Dietmar Eggemann f4904815f9 sched/deadline: Fix double accounting of rq/running bw in push & pull 
{push,pull}_dl_task() always calls {de,}activate_task() with .flags=0
which sets p->on_rq=TASK_ON_RQ_MIGRATING.

{push,pull}_dl_task()->{de,}activate_task()->{de,en}queue_task()->
{de,en}queue_task_dl() calls {sub,add}_{running,rq}_bw() since
p->on_rq==TASK_ON_RQ_MIGRATING.
So {sub,add}_{running,rq}_bw() in {push,pull}_dl_task() is
double-accounting for that task.

Fix it by removing rq/running bw accounting in [push/pull]_dl_task().

Fixes: 7dd7788411 ("sched/core: Unify p->on_rq updates")
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Luca Abeni <luca.abeni@santannapisa.it>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Qais Yousef <qais.yousef@arm.com>
Link: https://lkml.kernel.org/r/20190802145945.18702-2-dietmar.eggemann@arm.com
 2019-08-06 12:49:18 +02:00
Paul E. McKenney b55bd58555 time/tick-broadcast: Fix tick_broadcast_offline() lockdep complaint 
The TASKS03 and TREE04 rcutorture scenarios produce the following
lockdep complaint:

------------------------------------------------------------------------

================================
WARNING: inconsistent lock state
5.2.0-rc1+ #513 Not tainted
--------------------------------
inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.
migration/1/14 [HC0[0]:SC0[0]:HE1:SE1] takes:
(____ptrval____) (tick_broadcast_lock){?...}, at: tick_broadcast_offline+0xf/0x70
{IN-HARDIRQ-W} state was registered at:
  lock_acquire+0xb0/0x1c0
  _raw_spin_lock_irqsave+0x3c/0x50
  tick_broadcast_switch_to_oneshot+0xd/0x40
  tick_switch_to_oneshot+0x4f/0xd0
  hrtimer_run_queues+0xf3/0x130
  run_local_timers+0x1c/0x50
  update_process_times+0x1c/0x50
  tick_periodic+0x26/0xc0
  tick_handle_periodic+0x1a/0x60
  smp_apic_timer_interrupt+0x80/0x2a0
  apic_timer_interrupt+0xf/0x20
  _raw_spin_unlock_irqrestore+0x4e/0x60
  rcu_nocb_gp_kthread+0x15d/0x590
  kthread+0xf3/0x130
  ret_from_fork+0x3a/0x50
irq event stamp: 171
hardirqs last  enabled at (171): [<ffffffff8a201a37>] trace_hardirqs_on_thunk+0x1a/0x1c
hardirqs last disabled at (170): [<ffffffff8a201a53>] trace_hardirqs_off_thunk+0x1a/0x1c
softirqs last  enabled at (0): [<ffffffff8a264ee0>] copy_process.part.56+0x650/0x1cb0
softirqs last disabled at (0): [<0000000000000000>] 0x0

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(tick_broadcast_lock);
  <Interrupt>
    lock(tick_broadcast_lock);

 *** DEADLOCK ***

1 lock held by migration/1/14:
 #0: (____ptrval____) (clockevents_lock){+.+.}, at: tick_offline_cpu+0xf/0x30

stack backtrace:
CPU: 1 PID: 14 Comm: migration/1 Not tainted 5.2.0-rc1+ #513
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS Bochs 01/01/2011
Call Trace:
 dump_stack+0x5e/0x8b
 print_usage_bug+0x1fc/0x216
 ? print_shortest_lock_dependencies+0x1b0/0x1b0
 mark_lock+0x1f2/0x280
 __lock_acquire+0x1e0/0x18f0
 ? __lock_acquire+0x21b/0x18f0
 ? _raw_spin_unlock_irqrestore+0x4e/0x60
 lock_acquire+0xb0/0x1c0
 ? tick_broadcast_offline+0xf/0x70
 _raw_spin_lock+0x33/0x40
 ? tick_broadcast_offline+0xf/0x70
 tick_broadcast_offline+0xf/0x70
 tick_offline_cpu+0x16/0x30
 take_cpu_down+0x7d/0xa0
 multi_cpu_stop+0xa2/0xe0
 ? cpu_stop_queue_work+0xc0/0xc0
 cpu_stopper_thread+0x6d/0x100
 smpboot_thread_fn+0x169/0x240
 kthread+0xf3/0x130
 ? sort_range+0x20/0x20
 ? kthread_cancel_delayed_work_sync+0x10/0x10
 ret_from_fork+0x3a/0x50

------------------------------------------------------------------------

To reproduce, run the following rcutorture test:

        tools/testing/selftests/rcutorture/bin/kvm.sh --duration 5 --kconfig "CONFIG_DEBUG_LOCK_ALLOC=y CONFIG_PROVE_LOCKING=y" --configs "TASKS03 TREE04"

It turns out that tick_broadcast_offline() was an innocent bystander.
After all, interrupts are supposed to be disabled throughout
take_cpu_down(), and therefore should have been disabled upon entry to
tick_offline_cpu() and thus to tick_broadcast_offline().  This suggests
that one of the CPU-hotplug notifiers was incorrectly enabling interrupts,
and leaving them enabled on return.

Some debugging code showed that the culprit was sched_cpu_dying().
It had irqs enabled after return from sched_tick_stop().  Which in turn
had irqs enabled after return from cancel_delayed_work_sync().  Which is a
wrapper around __cancel_work_timer().  Which can sleep in the case where
something else is concurrently trying to cancel the same delayed work,
and as Thomas Gleixner pointed out on IRC, sleeping is a decidedly bad
idea when you are invoked from take_cpu_down(), regardless of the state
you leave interrupts in upon return.

Code inspection located no reason why the delayed work absolutely
needed to be canceled from sched_tick_stop():  The work is not
bound to the outgoing CPU by design, given that the whole point is
to collect statistics without disturbing the outgoing CPU.

This commit therefore simply drops the cancel_delayed_work_sync() from
sched_tick_stop().  Instead, a new ->state field is added to the tick_work
structure so that the delayed-work handler function sched_tick_remote()
can avoid reposting itself.  A cpu_is_offline() check is also added to
sched_tick_remote() to avoid mucking with the state of an offlined CPU
(though it does appear safe to do so).  The sched_tick_start() and
sched_tick_stop() functions also update ->state, and sched_tick_start()
also schedules the delayed work if ->state indicates that it is not
already in flight.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
[ paulmck: Apply Peter Zijlstra and Frederic Weisbecker atomics feedback. ]
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
 2019-08-01 14:05:51 -07:00
Juri Lelli 850377a875 sched/deadline: Ensure inactive_timer runs in hardirq context 
SCHED_DEADLINE inactive timer needs to run in hardirq context (as
dl_task_timer already does) on PREEMPT_RT

Change the mode to HRTIMER_MODE_REL_HARD.

[ tglx: Fixed up the start site, so mode debugging works ]

Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190731103715.4047-1-juri.lelli@redhat.com
 2019-08-01 20:51:22 +02:00
Sebastian Andrzej Siewior d5096aa65a sched: Mark hrtimers to expire in hard interrupt context 
The scheduler related hrtimers need to expire in hard interrupt context
even on PREEMPT_RT enabled kernels. Mark then as such.

No functional change.

[ tglx: Split out from larger combo patch. Add changelog. ]

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190726185753.077004842@linutronix.de
 2019-08-01 20:51:19 +02:00
Thomas Gleixner c1a280b68d sched/preempt: Use CONFIG_PREEMPTION where appropriate 
CONFIG_PREEMPTION is selected by CONFIG_PREEMPT and by
CONFIG_PREEMPT_RT. Both PREEMPT and PREEMPT_RT require the same
functionality which today depends on CONFIG_PREEMPT.

Switch the preemption code, scheduler and init task over to use
CONFIG_PREEMPTION.

That's the first step towards RT in that area. The more complex changes are
coming separately.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20190726212124.117528401@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-31 19:03:34 +02:00
Qian Cai a1dc0446d6 sched/core: Silence a warning in sched_init() 
Compiling a kernel with both FAIR_GROUP_SCHED=n and RT_GROUP_SCHED=n
will generate a compiler warning:

  kernel/sched/core.c: In function 'sched_init':
  kernel/sched/core.c:5906:32: warning: variable 'ptr' set but not used

It is unnecessary to have both "alloc_size" and "ptr", so just combine
them.

Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: valentin.schneider@arm.com
Link: https://lkml.kernel.org/r/20190720012319.884-1-cai@lca.pw
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-25 15:55:05 +02:00
Juri Lelli a07db5c086 sched/core: Fix CPU controller for !RT_GROUP_SCHED 
On !CONFIG_RT_GROUP_SCHED configurations it is currently not possible to
move RT tasks between cgroups to which CPU controller has been attached;
but it is oddly possible to first move tasks around and then make them
RT (setschedule to FIFO/RR).

E.g.:

  # mkdir /sys/fs/cgroup/cpu,cpuacct/group1
  # chrt -fp 10 $$
  # echo $$ > /sys/fs/cgroup/cpu,cpuacct/group1/tasks
  bash: echo: write error: Invalid argument
  # chrt -op 0 $$
  # echo $$ > /sys/fs/cgroup/cpu,cpuacct/group1/tasks
  # chrt -fp 10 $$
  # cat /sys/fs/cgroup/cpu,cpuacct/group1/tasks
  2345
  2598
  # chrt -p 2345
  pid 2345's current scheduling policy: SCHED_FIFO
  pid 2345's current scheduling priority: 10

Also, as Michal noted, it is currently not possible to enable CPU
controller on unified hierarchy with !CONFIG_RT_GROUP_SCHED (if there
are any kernel RT threads in root cgroup, they can't be migrated to the
newly created CPU controller's root in cgroup_update_dfl_csses()).

Existing code comes with a comment saying the "we don't support RT-tasks
being in separate groups". Such comment is however stale and belongs to
pre-RT_GROUP_SCHED times. Also, it doesn't make much sense for
!RT_GROUP_ SCHED configurations, since checks related to RT bandwidth
are not performed at all in these cases.

Make moving RT tasks between CPU controller groups viable by removing
special case check for RT (and DEADLINE) tasks.

Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: lizefan@huawei.com
Cc: longman@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: rostedt@goodmis.org
Link: https://lkml.kernel.org/r/20190719063455.27328-1-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-25 15:55:05 +02:00
Juri Lelli 710da3c8ea sched/core: Prevent race condition between cpuset and __sched_setscheduler() 
No synchronisation mechanism exists between the cpuset subsystem and
calls to function __sched_setscheduler(). As such, it is possible that
new root domains are created on the cpuset side while a deadline
acceptance test is carried out in __sched_setscheduler(), leading to a
potential oversell of CPU bandwidth.

Grab cpuset_rwsem read lock from core scheduler, so to prevent
situations such as the one described above from happening.

The only exception is normalize_rt_tasks() which needs to work under
tasklist_lock and can't therefore grab cpuset_rwsem. We are fine with
this, as this function is only called by sysrq and, if that gets
triggered, DEADLINE guarantees are already gone out of the window
anyway.

Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bristot@redhat.com
Cc: claudio@evidence.eu.com
Cc: lizefan@huawei.com
Cc: longman@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: mathieu.poirier@linaro.org
Cc: rostedt@goodmis.org
Cc: tj@kernel.org
Cc: tommaso.cucinotta@santannapisa.it
Link: https://lkml.kernel.org/r/20190719140000.31694-9-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-25 15:55:04 +02:00
Juri Lelli 59d06cea11 sched/deadline: Fix bandwidth accounting at all levels after offline migration 
If a task happens to be throttled while the CPU it was running on gets
hotplugged off, the bandwidth associated with the task is not correctly
migrated with it when the replenishment timer fires (offline_migration).

Fix things up, for this_bw, running_bw and total_bw, when replenishment
timer fires and task is migrated (dl_task_offline_migration()).

Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bristot@redhat.com
Cc: claudio@evidence.eu.com
Cc: lizefan@huawei.com
Cc: longman@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: mathieu.poirier@linaro.org
Cc: rostedt@goodmis.org
Cc: tj@kernel.org
Cc: tommaso.cucinotta@santannapisa.it
Link: https://lkml.kernel.org/r/20190719140000.31694-5-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-25 15:55:02 +02:00
Mathieu Poirier f9a25f776d cpusets: Rebuild root domain deadline accounting information 
When the topology of root domains is modified by CPUset or CPUhotplug
operations information about the current deadline bandwidth held in the
root domain is lost.

This patch addresses the issue by recalculating the lost deadline
bandwidth information by circling through the deadline tasks held in
CPUsets and adding their current load to the root domain they are
associated with.

Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
[ Various additional modifications. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bristot@redhat.com
Cc: claudio@evidence.eu.com
Cc: lizefan@huawei.com
Cc: longman@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: rostedt@goodmis.org
Cc: tj@kernel.org
Cc: tommaso.cucinotta@santannapisa.it
Link: https://lkml.kernel.org/r/20190719140000.31694-4-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-25 15:55:01 +02:00
Mathieu Poirier 4b211f2b12 sched/core: Streamle calls to task_rq_unlock() 
Calls to task_rq_unlock() are done several times in the
__sched_setscheduler() function.  This is fine when only the rq lock needs to be
handled but not so much when other locks come into play.

This patch streamlines the release of the rq lock so that only one
location need to be modified when dealing with more than one lock.

No change of functionality is introduced by this patch.

Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bristot@redhat.com
Cc: claudio@evidence.eu.com
Cc: lizefan@huawei.com
Cc: longman@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: tommaso.cucinotta@santannapisa.it
Link: https://lkml.kernel.org/r/20190719140000.31694-3-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-25 15:51:57 +02:00
Mathieu Poirier c22645f4c8 sched/topology: Add partition_sched_domains_locked() 
Introduce the partition_sched_domains_locked() function by taking
the mutex locking code out of the original function.  That way
the work done by partition_sched_domains_locked() can be reused
without dropping the mutex lock.

No change of functionality is introduced by this patch.

Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bristot@redhat.com
Cc: claudio@evidence.eu.com
Cc: lizefan@huawei.com
Cc: longman@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: rostedt@goodmis.org
Cc: tommaso.cucinotta@santannapisa.it
Link: https://lkml.kernel.org/r/20190719140000.31694-2-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-25 15:51:57 +02:00
Viresh Kumar 60e17f5cef sched/fair: Introduce fits_capacity() 
The same formula to check utilization against capacity (after
considering capacity_margin) is already used at 5 different locations.

This patch creates a new macro, fits_capacity(), which can be used from
all these locations without exposing the details of it and hence
simplify code.

All the 5 code locations are updated as well to use it..

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/b477ac75a2b163048bdaeb37f57b4c3f04f75a31.1559631700.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-25 15:51:56 +02:00
Wanpeng Li e0e8d4911e sched/isolation: Prefer housekeeping CPU in local node 
In real product setup, there will be houseeking CPUs in each nodes, it
is prefer to do housekeeping from local node, fallback to global online
cpumask if failed to find houseeking CPU from local node.

Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/1561711901-4755-2-git-send-email-wanpengli@tencent.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-25 15:51:55 +02:00
Yi Wang 65d74e9169 sched/stats: Fix unlikely() use of sched_info_on() 
sched_info_on() is called with unlikely hint, however, the test
is to be a constant(1) on which compiler will do nothing when
make defconfig, so remove the hint.

Also, fix a lack of {}.

Signed-off-by: Yi Wang <wang.yi59@zte.com.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: up2wing@gmail.com
Cc: wang.liang82@zte.com.cn
Cc: xue.zhihong@zte.com.cn
Link: https://lkml.kernel.org/r/1562301307-43002-1-git-send-email-wang.yi59@zte.com.cn
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-25 15:51:55 +02:00
Viresh Kumar 3c29e651e1 sched/fair: Fall back to sched-idle CPU if idle CPU isn't found 
We try to find an idle CPU to run the next task, but in case we don't
find an idle CPU it is better to pick a CPU which will run the task the
soonest, for performance reason.

A CPU which isn't idle but has only SCHED_IDLE activity queued on it
should be a good target based on this criteria as any normal fair task
will most likely preempt the currently running SCHED_IDLE task
immediately. In fact, choosing a SCHED_IDLE CPU over a fully idle one
shall give better results as it should be able to run the task sooner
than an idle CPU (which requires to be woken up from an idle state).

This patch updates both fast and slow paths with this optimization.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: chris.redpath@arm.com
Cc: quentin.perret@linaro.org
Cc: songliubraving@fb.com
Cc: steven.sistare@oracle.com
Cc: subhra.mazumdar@oracle.com
Cc: tkjos@google.com
Link: https://lkml.kernel.org/r/eeafa25fdeb6f6edd5b2da716bc8f0ba7708cbcf.1561523542.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-25 15:51:54 +02:00
Viresh Kumar 43e9f7f231 sched/fair: Start tracking SCHED_IDLE tasks count in cfs_rq 
Track how many tasks are present with SCHED_IDLE policy in each cfs_rq.
This will be used by later commits.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: chris.redpath@arm.com
Cc: quentin.perret@linaro.org
Cc: songliubraving@fb.com
Cc: steven.sistare@oracle.com
Cc: subhra.mazumdar@oracle.com
Cc: tkjos@google.com
Link: https://lkml.kernel.org/r/0d3cdc427fc68808ad5bccc40e86ed0bf9da8bb4.1561523542.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-25 15:51:53 +02:00
Paul E. McKenney 84ec3a0787 time/tick-broadcast: Fix tick_broadcast_offline() lockdep complaint 
time/tick-broadcast: Fix tick_broadcast_offline() lockdep complaint

The TASKS03 and TREE04 rcutorture scenarios produce the following
lockdep complaint:

	WARNING: inconsistent lock state
	5.2.0-rc1+ #513 Not tainted
	--------------------------------
	inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.
	migration/1/14 [HC0[0]:SC0[0]:HE1:SE1] takes:
	(____ptrval____) (tick_broadcast_lock){?...}, at: tick_broadcast_offline+0xf/0x70
	{IN-HARDIRQ-W} state was registered at:
	  lock_acquire+0xb0/0x1c0
	  _raw_spin_lock_irqsave+0x3c/0x50
	  tick_broadcast_switch_to_oneshot+0xd/0x40
	  tick_switch_to_oneshot+0x4f/0xd0
	  hrtimer_run_queues+0xf3/0x130
	  run_local_timers+0x1c/0x50
	  update_process_times+0x1c/0x50
	  tick_periodic+0x26/0xc0
	  tick_handle_periodic+0x1a/0x60
	  smp_apic_timer_interrupt+0x80/0x2a0
	  apic_timer_interrupt+0xf/0x20
	  _raw_spin_unlock_irqrestore+0x4e/0x60
	  rcu_nocb_gp_kthread+0x15d/0x590
	  kthread+0xf3/0x130
	  ret_from_fork+0x3a/0x50
	irq event stamp: 171
	hardirqs last  enabled at (171): [<ffffffff8a201a37>] trace_hardirqs_on_thunk+0x1a/0x1c
	hardirqs last disabled at (170): [<ffffffff8a201a53>] trace_hardirqs_off_thunk+0x1a/0x1c
	softirqs last  enabled at (0): [<ffffffff8a264ee0>] copy_process.part.56+0x650/0x1cb0
	softirqs last disabled at (0): [<0000000000000000>] 0x0

        [...]

To reproduce, run the following rcutorture test:

 $ tools/testing/selftests/rcutorture/bin/kvm.sh --duration 5 --kconfig "CONFIG_DEBUG_LOCK_ALLOC=y CONFIG_PROVE_LOCKING=y" --configs "TASKS03 TREE04"

It turns out that tick_broadcast_offline() was an innocent bystander.
After all, interrupts are supposed to be disabled throughout
take_cpu_down(), and therefore should have been disabled upon entry to
tick_offline_cpu() and thus to tick_broadcast_offline().  This suggests
that one of the CPU-hotplug notifiers was incorrectly enabling interrupts,
and leaving them enabled on return.

Some debugging code showed that the culprit was sched_cpu_dying().
It had irqs enabled after return from sched_tick_stop().  Which in turn
had irqs enabled after return from cancel_delayed_work_sync().  Which is a
wrapper around __cancel_work_timer().  Which can sleep in the case where
something else is concurrently trying to cancel the same delayed work,
and as Thomas Gleixner pointed out on IRC, sleeping is a decidedly bad
idea when you are invoked from take_cpu_down(), regardless of the state
you leave interrupts in upon return.

Code inspection located no reason why the delayed work absolutely
needed to be canceled from sched_tick_stop():  The work is not
bound to the outgoing CPU by design, given that the whole point is
to collect statistics without disturbing the outgoing CPU.

This commit therefore simply drops the cancel_delayed_work_sync() from
sched_tick_stop().  Instead, a new ->state field is added to the tick_work
structure so that the delayed-work handler function sched_tick_remote()
can avoid reposting itself.  A cpu_is_offline() check is also added to
sched_tick_remote() to avoid mucking with the state of an offlined CPU
(though it does appear safe to do so).  The sched_tick_start() and
sched_tick_stop() functions also update ->state, and sched_tick_start()
also schedules the delayed work if ->state indicates that it is not
already in flight.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
[ paulmck: Apply Peter Zijlstra and Frederic Weisbecker atomics feedback. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190625165238.GJ26519@linux.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-25 15:51:53 +02:00
Vincent Guittot f6cad8df6b sched/fair: Fix imbalance due to CPU affinity 
The load_balance() has a dedicated mecanism to detect when an imbalance
is due to CPU affinity and must be handled at parent level. In this case,
the imbalance field of the parent's sched_group is set.

The description of sg_imbalanced() gives a typical example of two groups
of 4 CPUs each and 4 tasks each with a cpumask covering 1 CPU of the first
group and 3 CPUs of the second group. Something like:

	{ 0 1 2 3 } { 4 5 6 7 }
	        *     * * *

But the load_balance fails to fix this UC on my octo cores system
made of 2 clusters of quad cores.

Whereas the load_balance is able to detect that the imbalanced is due to
CPU affinity, it fails to fix it because the imbalance field is cleared
before letting parent level a chance to run. In fact, when the imbalance is
detected, the load_balance reruns without the CPU with pinned tasks. But
there is no other running tasks in the situation described above and
everything looks balanced this time so the imbalance field is immediately
cleared.

The imbalance field should not be cleared if there is no other task to move
when the imbalance is detected.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/1561996022-28829-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-25 15:51:52 +02:00
Valentin Schneider 9434f9f5d1 sched/fair: Change task_numa_work() storage to static 
There are no callers outside of fair.c.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: mgorman@suse.de
Cc: riel@surriel.com
Link: https://lkml.kernel.org/r/20190715102508.32434-4-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-25 15:51:52 +02:00
Valentin Schneider b34920d4ce sched/fair: Move task_numa_work() init to init_numa_balancing() 
We only need to set the callback_head worker function once, do it
during sched_fork().

While at it, move the comment regarding double task_work addition to
init_numa_balancing(), since the double add sentinel is first set there.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: mgorman@suse.de
Cc: riel@surriel.com
Link: https://lkml.kernel.org/r/20190715102508.32434-3-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-25 15:51:51 +02:00
Valentin Schneider d35927a144 sched/fair: Move init_numa_balancing() below task_numa_work() 
To reference task_numa_work() from within init_numa_balancing(), we
need the former to be declared before the latter. Do just that.

This is a pure code movement.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: mgorman@suse.de
Cc: riel@surriel.com
Link: https://lkml.kernel.org/r/20190715102508.32434-2-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-25 15:51:51 +02:00
Jann Horn cb361d8cde sched/fair: Use RCU accessors consistently for ->numa_group 
The old code used RCU annotations and accessors inconsistently for
->numa_group, which can lead to use-after-frees and NULL dereferences.

Let all accesses to ->numa_group use proper RCU helpers to prevent such
issues.

Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Fixes: 8c8a743c50 ("sched/numa: Use {cpu, pid} to create task groups for shared faults")
Link: https://lkml.kernel.org/r/20190716152047.14424-3-jannh@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-25 15:37:05 +02:00
Jann Horn 16d51a590a sched/fair: Don't free p->numa_faults with concurrent readers 
When going through execve(), zero out the NUMA fault statistics instead of
freeing them.

During execve, the task is reachable through procfs and the scheduler. A
concurrent /proc/*/sched reader can read data from a freed ->numa_faults
allocation (confirmed by KASAN) and write it back to userspace.
I believe that it would also be possible for a use-after-free read to occur
through a race between a NUMA fault and execve(): task_numa_fault() can
lead to task_numa_compare(), which invokes task_weight() on the currently
running task of a different CPU.

Another way to fix this would be to make ->numa_faults RCU-managed or add
extra locking, but it seems easier to wipe the NUMA fault statistics on
execve.

Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Fixes: 82727018b0 ("sched/numa: Call task_numa_free() from do_execve()")
Link: https://lkml.kernel.org/r/20190716152047.14424-1-jannh@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-25 15:37:04 +02:00
Linus Torvalds 07ab9d5bc5 Mostly bugfixes, but also: 
- s390 support for KVM selftests
 - LAPIC timer offloading to housekeeping CPUs
 - Extend an s390 optimization for overcommitted hosts to all architectures
 - Debugging cleanups and improvements
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v2.0.22 (GNU/Linux)
 
 iQEcBAABAgAGBQJdMr1FAAoJEL/70l94x66DvIkH/iVuUX9jO1NoQ7qhxeo04MnT
 GP9mX3XnWoI/iN0zAIRfQSP2/9a6+KblgdiziABhju58j5dCfAZGb5793TQppweb
 3ubl11vy7YkzaXJ0b35K7CFhOU9oSlHHGyi5Uh+yyje5qWNxwmHpizxjynbFTKb6
 +/S7O2Ua1VrAVvx0i0IRtwanIK/jF4dStVButgVaVdUva3zLaQmeI71iaJl9ddXY
 bh50xoYua5Ek6+ENi+nwCNVy4OF152AwDbXlxrU0QbeA1B888Qio7nIqb3bwwPpZ
 /8wMVvPzQgL7RmgtY5E5Z4cCYuu7mK8wgGxhuk3oszlVwZJ5rmnaYwGEl4x1s7o=
 =giag
 -----END PGP SIGNATURE-----

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull more KVM updates from Paolo Bonzini:
 "Mostly bugfixes, but also:

   - s390 support for KVM selftests

   - LAPIC timer offloading to housekeeping CPUs

   - Extend an s390 optimization for overcommitted hosts to all
     architectures

   - Debugging cleanups and improvements"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (25 commits)
  KVM: x86: Add fixed counters to PMU filter
  KVM: nVMX: do not use dangling shadow VMCS after guest reset
  KVM: VMX: dump VMCS on failed entry
  KVM: x86/vPMU: refine kvm_pmu err msg when event creation failed
  KVM: s390: Use kvm_vcpu_wake_up in kvm_s390_vcpu_wakeup
  KVM: Boost vCPUs that are delivering interrupts
  KVM: selftests: Remove superfluous define from vmx.c
  KVM: SVM: Fix detection of AMD Errata 1096
  KVM: LAPIC: Inject timer interrupt via posted interrupt
  KVM: LAPIC: Make lapic timer unpinned
  KVM: x86/vPMU: reset pmc->counter to 0 for pmu fixed_counters
  KVM: nVMX: Ignore segment base for VMX memory operand when segment not FS or GS
  kvm: x86: ioapic and apic debug macros cleanup
  kvm: x86: some tsc debug cleanup
  kvm: vmx: fix coccinelle warnings
  x86: kvm: avoid constant-conversion warning
  x86: kvm: avoid -Wsometimes-uninitized warning
  KVM: x86: expose AVX512_BF16 feature to guest
  KVM: selftests: enable pgste option for the linker on s390
  KVM: selftests: Move kvm_create_max_vcpus test to generic code
  ...
 2019-07-20 10:20:27 -07:00
Wanpeng Li 0c5f81dad4 KVM: LAPIC: Inject timer interrupt via posted interrupt 
Dedicated instances are currently disturbed by unnecessary jitter due
to the emulated lapic timers firing on the same pCPUs where the
vCPUs reside.  There is no hardware virtual timer on Intel for guest
like ARM, so both programming timer in guest and the emulated timer fires
incur vmexits.  This patch tries to avoid vmexit when the emulated timer
fires, at least in dedicated instance scenario when nohz_full is enabled.

In that case, the emulated timers can be offload to the nearest busy
housekeeping cpus since APICv has been found for several years in server
processors. The guest timer interrupt can then be injected via posted interrupts,
which are delivered by the housekeeping cpu once the emulated timer fires.

The host should tuned so that vCPUs are placed on isolated physical
processors, and with several pCPUs surplus for busy housekeeping.
If disabled mwait/hlt/pause vmexits keep the vCPUs in non-root mode,
~3% redis performance benefit can be observed on Skylake server, and the
number of external interrupt vmexits drops substantially.  Without patch

            VM-EXIT  Samples  Samples%  Time%   Min Time  Max Time   Avg time
EXTERNAL_INTERRUPT    42916    49.43%   39.30%   0.47us   106.09us   0.71us ( +-   1.09% )

While with patch:

            VM-EXIT  Samples  Samples%  Time%   Min Time  Max Time         Avg time
EXTERNAL_INTERRUPT    6871     9.29%     2.96%   0.44us    57.88us   0.72us ( +-   4.02% )

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
 2019-07-20 09:00:40 +02:00
Peter Zijlstra e3d85487fb sched/core: Fix preempt warning in ttwu 
John reported a DEBUG_PREEMPT warning caused by commit:

  aacedf26fb ("sched/core: Optimize try_to_wake_up() for local wakeups")

I overlooked that ttwu_stat() requires preemption disabled.

Reported-by: John Stultz <john.stultz@linaro.org>
Tested-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: aacedf26fb ("sched/core: Optimize try_to_wake_up() for local wakeups")
Link: https://lkml.kernel.org/r/20190710105736.GK3402@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-07-13 11:23:27 +02:00
Linus Torvalds e9a83bd232 It's been a relatively busy cycle for docs: 
- A fair pile of RST conversions, many from Mauro.  These create more
    than the usual number of simple but annoying merge conflicts with other
    trees, unfortunately.  He has a lot more of these waiting on the wings
    that, I think, will go to you directly later on.
 
  - A new document on how to use merges and rebases in kernel repos, and one
    on Spectre vulnerabilities.
 
  - Various improvements to the build system, including automatic markup of
    function() references because some people, for reasons I will never
    understand, were of the opinion that :c:func:``function()`` is
    unattractive and not fun to type.
 
  - We now recommend using sphinx 1.7, but still support back to 1.4.
 
  - Lots of smaller improvements, warning fixes, typo fixes, etc.
 -----BEGIN PGP SIGNATURE-----
 
 iQFDBAABCAAtFiEEIw+MvkEiF49krdp9F0NaE2wMflgFAl0krAEPHGNvcmJldEBs
 d24ubmV0AAoJEBdDWhNsDH5Yg98H/AuLqO9LpOgUjF4LhyjxGPdzJkY9RExSJ7km
 gznyreLCZgFaJR+AY6YDsd4Jw6OJlPbu1YM/Qo3C3WrZVFVhgL/s2ebvBgCo50A8
 raAFd8jTf4/mGCHnAqRotAPQ3mETJUk315B66lBJ6Oc+YdpRhwXWq8ZW2bJxInFF
 3HDvoFgMf0KhLuMHUkkL0u3fxH1iA+KvDu8diPbJYFjOdOWENz/CV8wqdVkXRSEW
 DJxIq89h/7d+hIG3d1I7Nw+gibGsAdjSjKv4eRKauZs4Aoxd1Gpl62z0JNk6aT3m
 dtq4joLdwScydonXROD/Twn2jsu4xYTrPwVzChomElMowW/ZBBY=
 =D0eO
 -----END PGP SIGNATURE-----

Merge tag 'docs-5.3' of git://git.lwn.net/linux

Pull Documentation updates from Jonathan Corbet:
 "It's been a relatively busy cycle for docs:

   - A fair pile of RST conversions, many from Mauro. These create more
     than the usual number of simple but annoying merge conflicts with
     other trees, unfortunately. He has a lot more of these waiting on
     the wings that, I think, will go to you directly later on.

   - A new document on how to use merges and rebases in kernel repos,
     and one on Spectre vulnerabilities.

   - Various improvements to the build system, including automatic
     markup of function() references because some people, for reasons I
     will never understand, were of the opinion that
     :c:func:``function()`` is unattractive and not fun to type.

   - We now recommend using sphinx 1.7, but still support back to 1.4.

   - Lots of smaller improvements, warning fixes, typo fixes, etc"

* tag 'docs-5.3' of git://git.lwn.net/linux: (129 commits)
  docs: automarkup.py: ignore exceptions when seeking for xrefs
  docs: Move binderfs to admin-guide
  Disable Sphinx SmartyPants in HTML output
  doc: RCU callback locks need only _bh, not necessarily _irq
  docs: format kernel-parameters -- as code
  Doc : doc-guide : Fix a typo
  platform: x86: get rid of a non-existent document
  Add the RCU docs to the core-api manual
  Documentation: RCU: Add TOC tree hooks
  Documentation: RCU: Rename txt files to rst
  Documentation: RCU: Convert RCU UP systems to reST
  Documentation: RCU: Convert RCU linked list to reST
  Documentation: RCU: Convert RCU basic concepts to reST
  docs: filesystems: Remove uneeded .rst extension on toctables
  scripts/sphinx-pre-install: fix out-of-tree build
  docs: zh_CN: submitting-drivers.rst: Remove a duplicated Documentation/
  Documentation: PGP: update for newer HW devices
  Documentation: Add section about CPU vulnerabilities for Spectre
  Documentation: platform: Delete x86-laptop-drivers.txt
  docs: Note that :c:func: should no longer be used
  ...
 2019-07-09 12:34:26 -07:00
Linus Torvalds dad1c12ed8 Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 
Pull scheduler updates from Ingo Molnar:

 - Remove the unused per rq load array and all its infrastructure, by
   Dietmar Eggemann.

 - Add utilization clamping support by Patrick Bellasi. This is a
   refinement of the energy aware scheduling framework with support for
   boosting of interactive and capping of background workloads: to make
   sure critical GUI threads get maximum frequency ASAP, and to make
   sure background processing doesn't unnecessarily move to cpufreq
   governor to higher frequencies and less energy efficient CPU modes.

 - Add the bare minimum of tracepoints required for LISA EAS regression
   testing, by Qais Yousef - which allows automated testing of various
   power management features, including energy aware scheduling.

 - Restructure the former tsk_nr_cpus_allowed() facility that the -rt
   kernel used to modify the scheduler's CPU affinity logic such as
   migrate_disable() - introduce the task->cpus_ptr value instead of
   taking the address of &task->cpus_allowed directly - by Sebastian
   Andrzej Siewior.

 - Misc optimizations, fixes, cleanups and small enhancements - see the
   Git log for details.

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits)
  sched/uclamp: Add uclamp support to energy_compute()
  sched/uclamp: Add uclamp_util_with()
  sched/cpufreq, sched/uclamp: Add clamps for FAIR and RT tasks
  sched/uclamp: Set default clamps for RT tasks
  sched/uclamp: Reset uclamp values on RESET_ON_FORK
  sched/uclamp: Extend sched_setattr() to support utilization clamping
  sched/core: Allow sched_setattr() to use the current policy
  sched/uclamp: Add system default clamps
  sched/uclamp: Enforce last task's UCLAMP_MAX
  sched/uclamp: Add bucket local max tracking
  sched/uclamp: Add CPU's clamp buckets refcounting
  sched/fair: Rename weighted_cpuload() to cpu_runnable_load()
  sched/debug: Export the newly added tracepoints
  sched/debug: Add sched_overutilized tracepoint
  sched/debug: Add new tracepoint to track PELT at se level
  sched/debug: Add new tracepoints to track PELT at rq level
  sched/debug: Add a new sched_trace_*() helper functions
  sched/autogroup: Make autogroup_path() always available
  sched/wait: Deduplicate code with do-while
  sched/topology: Remove unused 'sd' parameter from arch_scale_cpu_capacity()
  ...
 2019-07-08 16:39:53 -07:00
Linus Torvalds e192832869 Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 
Pull locking updates from Ingo Molnar:
 "The main changes in this cycle are:

   - rwsem scalability improvements, phase #2, by Waiman Long, which are
     rather impressive:

       "On a 2-socket 40-core 80-thread Skylake system with 40 reader
        and writer locking threads, the min/mean/max locking operations
        done in a 5-second testing window before the patchset were:

         40 readers, Iterations Min/Mean/Max = 1,807/1,808/1,810
         40 writers, Iterations Min/Mean/Max = 1,807/50,344/151,255

        After the patchset, they became:

         40 readers, Iterations Min/Mean/Max = 30,057/31,359/32,741
         40 writers, Iterations Min/Mean/Max = 94,466/95,845/97,098"

     There's a lot of changes to the locking implementation that makes
     it similar to qrwlock, including owner handoff for more fair
     locking.

     Another microbenchmark shows how across the spectrum the
     improvements are:

       "With a locking microbenchmark running on 5.1 based kernel, the
        total locking rates (in kops/s) on a 2-socket Skylake system
        with equal numbers of readers and writers (mixed) before and
        after this patchset were:

        # of Threads   Before Patch      After Patch
        ------------   ------------      -----------
             2            2,618             4,193
             4            1,202             3,726
             8              802             3,622
            16              729             3,359
            32              319             2,826
            64              102             2,744"

     The changes are extensive and the patch-set has been through
     several iterations addressing various locking workloads. There
     might be more regressions, but unless they are pathological I
     believe we want to use this new implementation as the baseline
     going forward.

   - jump-label optimizations by Daniel Bristot de Oliveira: the primary
     motivation was to remove IPI disturbance of isolated RT-workload
     CPUs, which resulted in the implementation of batched jump-label
     updates. Beyond the improvement of the real-time characteristics
     kernel, in one test this patchset improved static key update
     overhead from 57 msecs to just 1.4 msecs - which is a nice speedup
     as well.

   - atomic64_t cross-arch type cleanups by Mark Rutland: over the last
     ~10 years of atomic64_t existence the various types used by the
     APIs only had to be self-consistent within each architecture -
     which means they became wildly inconsistent across architectures.
     Mark puts and end to this by reworking all the atomic64
     implementations to use 's64' as the base type for atomic64_t, and
     to ensure that this type is consistently used for parameters and
     return values in the API, avoiding further problems in this area.

   - A large set of small improvements to lockdep by Yuyang Du: type
     cleanups, output cleanups, function return type and othr cleanups
     all around the place.

   - A set of percpu ops cleanups and fixes by Peter Zijlstra.

   - Misc other changes - please see the Git log for more details"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (82 commits)
  locking/lockdep: increase size of counters for lockdep statistics
  locking/atomics: Use sed(1) instead of non-standard head(1) option
  locking/lockdep: Move mark_lock() inside CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING
  x86/jump_label: Make tp_vec_nr static
  x86/percpu: Optimize raw_cpu_xchg()
  x86/percpu, sched/fair: Avoid local_clock()
  x86/percpu, x86/irq: Relax {set,get}_irq_regs()
  x86/percpu: Relax smp_processor_id()
  x86/percpu: Differentiate this_cpu_{}() and __this_cpu_{}()
  locking/rwsem: Guard against making count negative
  locking/rwsem: Adaptive disabling of reader optimistic spinning
  locking/rwsem: Enable time-based spinning on reader-owned rwsem
  locking/rwsem: Make rwsem->owner an atomic_long_t
  locking/rwsem: Enable readers spinning on writer
  locking/rwsem: Clarify usage of owner's nonspinaable bit
  locking/rwsem: Wake up almost all readers in wait queue
  locking/rwsem: More optimal RT task handling of null owner
  locking/rwsem: Always release wait_lock before waking up tasks
  locking/rwsem: Implement lock handoff to prevent lock starvation
  locking/rwsem: Make rwsem_spin_on_owner() return owner state
  ...
 2019-07-08 16:12:03 -07:00
Patrick Bellasi af24bde8df sched/uclamp: Add uclamp support to energy_compute() 
The Energy Aware Scheduler (EAS) estimates the energy impact of waking
up a task on a given CPU. This estimation is based on:

 a) an (active) power consumption defined for each CPU frequency
 b) an estimation of which frequency will be used on each CPU
 c) an estimation of the busy time (utilization) of each CPU

Utilization clamping can affect both b) and c).

A CPU is expected to run:

 - on an higher than required frequency, but for a shorter time, in case
   its estimated utilization will be smaller than the minimum utilization
   enforced by uclamp
 - on a smaller than required frequency, but for a longer time, in case
   its estimated utilization is bigger than the maximum utilization
   enforced by uclamp

While compute_energy() already accounts clamping effects on busy time,
the clamping effects on frequency selection are currently ignored.

Fix it by considering how CPU clamp values will be affected by a
task waking up and being RUNNABLE on that CPU.

Do that by refactoring schedutil_freq_util() to take an additional
task_struct* which allows EAS to evaluate the impact on clamp values of
a task being eventually queued in a CPU. Clamp values are applied to the
RT+CFS utilization only when a FREQUENCY_UTIL is required by
compute_energy().

Do note that switching from ENERGY_UTIL to FREQUENCY_UTIL in the
computation of the cpu_util signal implies that we are more likely to
estimate the highest OPP when a RT task is running in another CPU of
the same performance domain. This can have an impact on energy
estimation but:

 - it's not easy to say which approach is better, since it depends on
   the use case
 - the original approach could still be obtained by setting a smaller
   task-specific util_min whenever required

Since we are at that:

 - rename schedutil_freq_util() into schedutil_cpu_util(),
   since it's not only used for frequency selection.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-12-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:23:49 +02:00
Patrick Bellasi 9d20ad7dfc sched/uclamp: Add uclamp_util_with() 
So far uclamp_util() allows to clamp a specified utilization considering
the clamp values requested by RUNNABLE tasks in a CPU. For the Energy
Aware Scheduler (EAS) it is interesting to test how clamp values will
change when a task is becoming RUNNABLE on a given CPU.
For example, EAS is interested in comparing the energy impact of
different scheduling decisions and the clamp values can play a role on
that.

Add uclamp_util_with() which allows to clamp a given utilization by
considering the possible impact on CPU clamp values of a specified task.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-11-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:23:48 +02:00
Patrick Bellasi 982d9cdc22 sched/cpufreq, sched/uclamp: Add clamps for FAIR and RT tasks 
Each time a frequency update is required via schedutil, a frequency is
selected to (possibly) satisfy the utilization reported by each
scheduling class and irqs. However, when utilization clamping is in use,
the frequency selection should consider userspace utilization clamping
hints.  This will allow, for example, to:

 - boost tasks which are directly affecting the user experience
   by running them at least at a minimum "requested" frequency

 - cap low priority tasks not directly affecting the user experience
   by running them only up to a maximum "allowed" frequency

These constraints are meant to support a per-task based tuning of the
frequency selection thus supporting a fine grained definition of
performance boosting vs energy saving strategies in kernel space.

Add support to clamp the utilization of RUNNABLE FAIR and RT tasks
within the boundaries defined by their aggregated utilization clamp
constraints.

Do that by considering the max(min_util, max_util) to give boosted tasks
the performance they need even when they happen to be co-scheduled with
other capped tasks.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-10-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:23:48 +02:00
Patrick Bellasi 1a00d99997 sched/uclamp: Set default clamps for RT tasks 
By default FAIR tasks start without clamps, i.e. neither boosted nor
capped, and they run at the best frequency matching their utilization
demand.  This default behavior does not fit RT tasks which instead are
expected to run at the maximum available frequency, if not otherwise
required by explicitly capping them.

Enforce the correct behavior for RT tasks by setting util_min to max
whenever:

 1. the task is switched to the RT class and it does not already have a
    user-defined clamp value assigned.

 2. an RT task is forked from a parent with RESET_ON_FORK set.

NOTE: utilization clamp values are cross scheduling class attributes and
thus they are never changed/reset once a value has been explicitly
defined from user-space.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-9-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:23:47 +02:00
Patrick Bellasi a87498ace5 sched/uclamp: Reset uclamp values on RESET_ON_FORK 
A forked tasks gets the same clamp values of its parent however, when
the RESET_ON_FORK flag is set on parent, e.g. via:

   sys_sched_setattr()
      sched_setattr()
         __sched_setscheduler(attr::SCHED_FLAG_RESET_ON_FORK)

the new forked task is expected to start with all attributes reset to
default values.

Do that for utilization clamp values too by checking the reset request
from the existing uclamp_fork() call which already provides the required
initialization for other uclamp related bits.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-8-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:23:47 +02:00
Patrick Bellasi a509a7cd79 sched/uclamp: Extend sched_setattr() to support utilization clamping 
The SCHED_DEADLINE scheduling class provides an advanced and formal
model to define tasks requirements that can translate into proper
decisions for both task placements and frequencies selections. Other
classes have a more simplified model based on the POSIX concept of
priorities.

Such a simple priority based model however does not allow to exploit
most advanced features of the Linux scheduler like, for example, driving
frequencies selection via the schedutil cpufreq governor. However, also
for non SCHED_DEADLINE tasks, it's still interesting to define tasks
properties to support scheduler decisions.

Utilization clamping exposes to user-space a new set of per-task
attributes the scheduler can use as hints about the expected/required
utilization for a task. This allows to implement a "proactive" per-task
frequency control policy, a more advanced policy than the current one
based just on "passive" measured task utilization. For example, it's
possible to boost interactive tasks (e.g. to get better performance) or
cap background tasks (e.g. to be more energy/thermal efficient).

Introduce a new API to set utilization clamping values for a specified
task by extending sched_setattr(), a syscall which already allows to
define task specific properties for different scheduling classes. A new
pair of attributes allows to specify a minimum and maximum utilization
the scheduler can consider for a task.

Do that by validating the required clamp values before and then applying
the required changes using _the_ same pattern already in use for
__setscheduler(). This ensures that the task is re-enqueued with the new
clamp values.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-7-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:23:46 +02:00
Patrick Bellasi 1d6362fa0c sched/core: Allow sched_setattr() to use the current policy 
The sched_setattr() syscall mandates that a policy is always specified.
This requires to always know which policy a task will have when
attributes are configured and this makes it impossible to add more
generic task attributes valid across different scheduling policies.
Reading the policy before setting generic tasks attributes is racy since
we cannot be sure it is not changed concurrently.

Introduce the required support to change generic task attributes without
affecting the current task policy. This is done by adding an attribute flag
(SCHED_FLAG_KEEP_POLICY) to enforce the usage of the current policy.

Add support for the SETPARAM_POLICY policy, which is already used by the
sched_setparam() POSIX syscall, to the sched_setattr() non-POSIX
syscall.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-6-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:23:46 +02:00
Patrick Bellasi e8f14172c6 sched/uclamp: Add system default clamps 
Tasks without a user-defined clamp value are considered not clamped
and by default their utilization can have any value in the
[0..SCHED_CAPACITY_SCALE] range.

Tasks with a user-defined clamp value are allowed to request any value
in that range, and the required clamp is unconditionally enforced.
However, a "System Management Software" could be interested in limiting
the range of clamp values allowed for all tasks.

Add a privileged interface to define a system default configuration via:

  /proc/sys/kernel/sched_uclamp_util_{min,max}

which works as an unconditional clamp range restriction for all tasks.

With the default configuration, the full SCHED_CAPACITY_SCALE range of
values is allowed for each clamp index. Otherwise, the task-specific
clamp is capped by the corresponding system default value.

Do that by tracking, for each task, the "effective" clamp value and
bucket the task has been refcounted in at enqueue time. This
allows to lazy aggregate "requested" and "system default" values at
enqueue time and simplifies refcounting updates at dequeue time.

The cached bucket ids are used to avoid (relatively) more expensive
integer divisions every time a task is enqueued.

An active flag is used to report when the "effective" value is valid and
thus the task is actually refcounted in the corresponding rq's bucket.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-5-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:23:45 +02:00
Patrick Bellasi e496187da7 sched/uclamp: Enforce last task's UCLAMP_MAX 
When a task sleeps it removes its max utilization clamp from its CPU.
However, the blocked utilization on that CPU can be higher than the max
clamp value enforced while the task was running. This allows undesired
CPU frequency increases while a CPU is idle, for example, when another
CPU on the same frequency domain triggers a frequency update, since
schedutil can now see the full not clamped blocked utilization of the
idle CPU.

Fix this by using:

  uclamp_rq_dec_id(p, rq, UCLAMP_MAX)
    uclamp_rq_max_value(rq, UCLAMP_MAX, clamp_value)

to detect when a CPU has no more RUNNABLE clamped tasks and to flag this
condition.

Don't track any minimum utilization clamps since an idle CPU never
requires a minimum frequency. The decay of the blocked utilization is
good enough to reduce the CPU frequency.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-4-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:23:45 +02:00
Patrick Bellasi 60daf9c194 sched/uclamp: Add bucket local max tracking 
Because of bucketization, different task-specific clamp values are
tracked in the same bucket.  For example, with 20% bucket size and
assuming to have:

  Task1: util_min=25%
  Task2: util_min=35%

both tasks will be refcounted in the [20..39]% bucket and always boosted
only up to 20% thus implementing a simple floor aggregation normally
used in histograms.

In systems with only few and well-defined clamp values, it would be
useful to track the exact clamp value required by a task whenever
possible. For example, if a system requires only 23% and 47% boost
values then it's possible to track the exact boost required by each
task using only 3 buckets of ~33% size each.

Introduce a mechanism to max aggregate the requested clamp values of
RUNNABLE tasks in the same bucket. Keep it simple by resetting the
bucket value to its base value only when a bucket becomes inactive.
Allow a limited and controlled overboosting margin for tasks recounted
in the same bucket.

In systems where the boost values are not known in advance, it is still
possible to control the maximum acceptable overboosting margin by tuning
the number of clamp groups. For example, 20 groups ensure a 5% maximum
overboost.

Remove the rq bucket initialization code since a correct bucket value
is now computed when a task is refcounted into a CPU's rq.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-3-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:23:44 +02:00
Patrick Bellasi 69842cba9a sched/uclamp: Add CPU's clamp buckets refcounting 
Utilization clamping allows to clamp the CPU's utilization within a
[util_min, util_max] range, depending on the set of RUNNABLE tasks on
that CPU. Each task references two "clamp buckets" defining its minimum
and maximum (util_{min,max}) utilization "clamp values". A CPU's clamp
bucket is active if there is at least one RUNNABLE tasks enqueued on
that CPU and refcounting that bucket.

When a task is {en,de}queued {on,from} a rq, the set of active clamp
buckets on that CPU can change. If the set of active clamp buckets
changes for a CPU a new "aggregated" clamp value is computed for that
CPU. This is because each clamp bucket enforces a different utilization
clamp value.

Clamp values are always MAX aggregated for both util_min and util_max.
This ensures that no task can affect the performance of other
co-scheduled tasks which are more boosted (i.e. with higher util_min
clamp) or less capped (i.e. with higher util_max clamp).

A task has:
   task_struct::uclamp[clamp_id]::bucket_id
to track the "bucket index" of the CPU's clamp bucket it refcounts while
enqueued, for each clamp index (clamp_id).

A runqueue has:
   rq::uclamp[clamp_id]::bucket[bucket_id].tasks
to track how many RUNNABLE tasks on that CPU refcount each
clamp bucket (bucket_id) of a clamp index (clamp_id).
It also has a:
   rq::uclamp[clamp_id]::bucket[bucket_id].value
to track the clamp value of each clamp bucket (bucket_id) of a clamp
index (clamp_id).

The rq::uclamp::bucket[clamp_id][] array is scanned every time it's
needed to find a new MAX aggregated clamp value for a clamp_id. This
operation is required only when it's dequeued the last task of a clamp
bucket tracking the current MAX aggregated clamp value. In this case,
the CPU is either entering IDLE or going to schedule a less boosted or
more clamped task.
The expected number of different clamp values configured at build time
is small enough to fit the full unordered array into a single cache
line, for configurations of up to 7 buckets.

Add to struct rq the basic data structures required to refcount the
number of RUNNABLE tasks for each clamp bucket. Add also the max
aggregation required to update the rq's clamp value at each
enqueue/dequeue event.

Use a simple linear mapping of clamp values into clamp buckets.
Pre-compute and cache bucket_id to avoid integer divisions at
enqueue/dequeue time.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-2-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:23:44 +02:00
Dietmar Eggemann a3df067974 sched/fair: Rename weighted_cpuload() to cpu_runnable_load() 
The term 'weighted' is not needed since there is no 'unweighted' load.
Instead use the term 'runnable' to distinguish 'runnable' load
(avg.runnable_load_avg) used in load balance from load (avg.load_avg)
which is the sum of 'runnable' and 'blocked' load.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/57f27a7f-2775-d832-e965-0f4d51bb1954@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:23:43 +02:00
Qais Yousef a056a5bed7 sched/debug: Export the newly added tracepoints 
So that external modules can hook into them and extract the info they
need. Since these new tracepoints have no events associated with them
exporting these tracepoints make them useful for external modules to
perform testing and debugging. There's no other way otherwise to access
them.

BPF doesn't have infrastructure to access these bare tracepoints either.

Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavankumar Kondeti <pkondeti@codeaurora.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Uwe Kleine-Konig <u.kleine-koenig@pengutronix.de>
Link: https://lkml.kernel.org/r/20190604111459.2862-7-qais.yousef@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:23:43 +02:00
Qais Yousef f9f240f96e sched/debug: Add sched_overutilized tracepoint 
The new tracepoint allows us to track the changes in overutilized
status.

Overutilized status is associated with EAS. It indicates that the system
is in high performance state. EAS is disabled when the system is in this
state since there's not much energy savings while high performance tasks
are pushing the system to the limit and it's better to default to the
spreading behavior of the scheduler.

This tracepoint helps understanding and debugging the conditions under
which this happens.

Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavankumar Kondeti <pkondeti@codeaurora.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Uwe Kleine-Konig <u.kleine-koenig@pengutronix.de>
Link: https://lkml.kernel.org/r/20190604111459.2862-6-qais.yousef@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:23:42 +02:00
Qais Yousef 8de6242cca sched/debug: Add new tracepoint to track PELT at se level 
The new tracepoint allows tracking PELT signals at sched_entity level.
Which is supported in CFS tasks and taskgroups only.

Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavankumar Kondeti <pkondeti@codeaurora.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Uwe Kleine-Konig <u.kleine-koenig@pengutronix.de>
Link: https://lkml.kernel.org/r/20190604111459.2862-5-qais.yousef@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:23:42 +02:00
Qais Yousef ba19f51fcb sched/debug: Add new tracepoints to track PELT at rq level 
The new tracepoints allow tracking PELT signals at rq level for all
scheduling classes + irq.

Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavankumar Kondeti <pkondeti@codeaurora.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Uwe Kleine-Konig <u.kleine-koenig@pengutronix.de>
Link: https://lkml.kernel.org/r/20190604111459.2862-4-qais.yousef@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:23:41 +02:00
Qais Yousef 3c93a0c04d sched/debug: Add a new sched_trace_*() helper functions 
The new functions allow modules to access internal data structures of
unexported struct cfs_rq and struct rq to extract important information
from the tracepoints to be introduced in later patches.

While at it fix alphabetical order of struct declarations in sched.h

Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavankumar Kondeti <pkondeti@codeaurora.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Uwe Kleine-Konig <u.kleine-koenig@pengutronix.de>
Link: https://lkml.kernel.org/r/20190604111459.2862-3-qais.yousef@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:23:41 +02:00
Qais Yousef 9ba5090aec sched/autogroup: Make autogroup_path() always available 
Remove the #ifdef CONFIG_SCHED_DEBUG.

Some of the tracepoints to be introduced in later patches need to access
this function. Hence make it always available since the tracepoints are
not protected by CONFIG_SCHED_DEBUG.

Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavankumar Kondeti <pkondeti@codeaurora.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Uwe Kleine-Konig <u.kleine-koenig@pengutronix.de>
Link: https://lkml.kernel.org/r/20190604111459.2862-2-qais.yousef@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:23:40 +02:00
Pavel Begunkov 016190a4b5 sched/wait: Deduplicate code with do-while 
Statements in the loop's body and before it are identical.
Use do-while to not repeat it.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/43ffea6ee2152b90dedf962eac851609e4197218.1560256112.git.asml.silence@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:23:40 +02:00
Vincent Guittot 8ec59c0f5f sched/topology: Remove unused 'sd' parameter from arch_scale_cpu_capacity() 
The 'struct sched_domain *sd' parameter to arch_scale_cpu_capacity() is
unused since commit:

  765d0af19f ("sched/topology: Remove the ::smt_gain field from 'struct sched_domain'")

Remove it.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: gregkh@linuxfoundation.org
Cc: linux@armlinux.org.uk
Cc: quentin.perret@arm.com
Cc: rafael@kernel.org
Link: https://lkml.kernel.org/r/1560783617-5827-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:23:39 +02:00
Ingo Molnar d2abae71eb Linux 5.2-rc6 
-----BEGIN PGP SIGNATURE-----
 
 iQFSBAABCAA8FiEEq68RxlopcLEwq+PEeb4+QwBBGIYFAl0Os1seHHRvcnZhbGRz
 QGxpbnV4LWZvdW5kYXRpb24ub3JnAAoJEHm+PkMAQRiGtx4H/j6i482XzcGFKTBm
 A7mBoQpy+kLtoUov4EtBAR62OuwI8rsahW9di37QKndPoQrczWaKBmr3De6LCdPe
 v3pl3O6wBbvH5ru+qBPFX9PdNbDvimEChh7LHxmMxNQq3M+AjZAZVJyfpoiFnx35
 Fbge+LZaH/k8HMwZmkMr5t9Mpkip715qKg2o9Bua6dkH0AqlcpLlC8d9a+HIVw/z
 aAsyGSU8jRwhoAOJsE9bJf0acQ/pZSqmFp0rDKqeFTSDMsbDRKLGq/dgv4nW0RiW
 s7xqsjb/rdcvirRj3rv9+lcTVkOtEqwk0PVdL9WOf7g4iYrb3SOIZh8ZyViaDSeH
 VTS5zps=
 =huBY
 -----END PGP SIGNATURE-----

Merge tag 'v5.2-rc6' into sched/core, to refresh the branch

Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-24 19:19:53 +02:00
Thomas Gleixner d2912cb15b treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 
Based on 2 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 2019-06-19 17:09:55 +02:00
Peter Zijlstra 8dc2d993cf x86/percpu, sched/fair: Avoid local_clock() 
Nadav reported that code-gen changed because of the this_cpu_*()
constraints, avoid this for select_idle_cpu() because that runs with
preemption (and IRQs) disabled anyway.

Reported-by: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-17 12:43:43 +02:00
bsegall@google.com 66567fcbae sched/fair: Don't push cfs_bandwith slack timers forward 
When a cfs_rq sleeps and returns its quota, we delay for 5ms before
waking any throttled cfs_rqs to coalesce with other cfs_rqs going to
sleep, as this has to be done outside of the rq lock we hold.

The current code waits for 5ms without any sleeps, instead of waiting
for 5ms from the first sleep, which can delay the unthrottle more than
we want. Switch this around so that we can't push this forward forever.

This requires an extra flag rather than using hrtimer_active, since we
need to start a new timer if the current one is in the process of
finishing.

Signed-off-by: Ben Segall <bsegall@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Xunlei Pang <xlpang@linux.alibaba.com>
Acked-by: Phil Auld <pauld@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/xm26a7euy6iq.fsf_-_@bsegall-linux.svl.corp.google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-17 12:16:01 +02:00
Peter Zijlstra aacedf26fb sched/core: Optimize try_to_wake_up() for local wakeups 
Jens reported that significant performance can be had on some block
workloads by special casing local wakeups. That is, wakeups on the
current task before it schedules out.

Given something like the normal wait pattern:

	for (;;) {
		set_current_state(TASK_UNINTERRUPTIBLE);

		if (cond)
			break;

		schedule();
	}
	__set_current_state(TASK_RUNNING);

Any wakeup (on this CPU) after set_current_state() and before
schedule() would benefit from this.

Normal wakeups take p->pi_lock, which serializes wakeups to the same
task. By eliding that we gain concurrency on:

 - ttwu_stat(); we already had concurrency on rq stats, this now also
   brings it to task stats. -ENOCARE

 - tracepoints; it is now possible to get multiple instances of
   trace_sched_waking() (and possibly trace_sched_wakeup()) for the
   same task. Tracers will have to learn to cope.

Furthermore, p->pi_lock is used by set_special_state(), to order
against TASK_RUNNING stores from other CPUs. But since this is
strictly CPU local, we don't need the lock, and set_special_state()'s
disabling of IRQs is sufficient.

After the normal wakeup takes p->pi_lock it issues
smp_mb__after_spinlock(), in order to ensure the woken task must
observe prior stores before we observe the p->state. If this is CPU
local, this will be satisfied with a compiler barrier, and we rely on
try_to_wake_up() being a funcation call, which implies such.

Since, when 'p == current', 'p->on_rq' must be true, the normal wakeup
would continue into the ttwu_remote() branch, which normally is
concerned with exactly this wakeup scenario, except from a remote CPU.
IOW we're waking a task that is still running. In this case, we can
trivially avoid taking rq->lock, all that's left from this is to set
p->state.

This then yields an extremely simple and fast path for 'p == current'.

Reported-by: Jens Axboe <axboe@kernel.dk>
Tested-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: gkohli@codeaurora.org
Cc: hch@lst.de
Cc: oleg@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-17 12:15:59 +02:00
Qian Cai 509466b7d4 sched/fair: Fix "runnable_avg_yN_inv" not used warnings 
runnable_avg_yN_inv[] is only used in kernel/sched/pelt.c but was
included in several other places because they need other macros all
came from kernel/sched/sched-pelt.h which was generated by
Documentation/scheduler/sched-pelt. As the result, it causes compilation
a lot of warnings,

  kernel/sched/sched-pelt.h:4:18: warning: 'runnable_avg_yN_inv' defined but not used [-Wunused-const-variable=]
  kernel/sched/sched-pelt.h:4:18: warning: 'runnable_avg_yN_inv' defined but not used [-Wunused-const-variable=]
  kernel/sched/sched-pelt.h:4:18: warning: 'runnable_avg_yN_inv' defined but not used [-Wunused-const-variable=]
  ...

Silence it by appending the __maybe_unused attribute for it, so all
generated variables and macros can still be kept in the same file.

Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/1559596304-31581-1-git-send-email-cai@lca.pw
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-17 12:15:58 +02:00
Valentin Schneider b0c7922441 sched/fair: Clean up definition of NOHZ blocked load functions 
cfs_rq_has_blocked() and others_have_blocked() are only used within
update_blocked_averages(). The !CONFIG_FAIR_GROUP_SCHED version of the
latter calls them within a #define CONFIG_NO_HZ_COMMON block, whereas
the CONFIG_FAIR_GROUP_SCHED one calls them unconditionnally.

As reported by Qian, the above leads to this warning in
!CONFIG_NO_HZ_COMMON configs:

  kernel/sched/fair.c: In function 'update_blocked_averages':
  kernel/sched/fair.c:7750:7: warning: variable 'done' set but not used [-Wunused-but-set-variable]

It wouldn't be wrong to keep cfs_rq_has_blocked() and
others_have_blocked() as they are, but since their only current use is
to figure out when we can stop calling update_blocked_averages() on
fully decayed NOHZ idle CPUs, we can give them a new definition for
!CONFIG_NO_HZ_COMMON.

Change the definition of cfs_rq_has_blocked() and
others_have_blocked() for !CONFIG_NO_HZ_COMMON so that the
NOHZ-specific blocks of update_blocked_averages() become no-ops and
the 'done' variable gets optimised out.

While at it, remove the CONFIG_NO_HZ_COMMON block from the
!CONFIG_FAIR_GROUP_SCHED definition of update_blocked_averages() by
using the newly-introduced update_blocked_load_status() helper.

No change in functionality intended.

[ Additions by Peter Zijlstra. ]

Reported-by: Qian Cai <cai@lca.pw>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190603115424.7951-1-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-17 12:15:57 +02:00
Gao Xiang e3b929b0a1 sched/core: Add __sched tag for io_schedule() 
Non-inline io_schedule() was introduced in:

  commit 10ab56434f ("sched/core: Separate out io_schedule_prepare() and io_schedule_finish()")

Keep in line with io_schedule_timeout(), otherwise "/proc/<pid>/wchan" will
report io_schedule() rather than its callers when waiting for IO.

Reported-by: Jilong Kou <koujilong@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Miao Xie <miaoxie@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 10ab56434f ("sched/core: Separate out io_schedule_prepare() and io_schedule_finish()")
Link: https://lkml.kernel.org/r/20190603091338.2695-1-gaoxiang25@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-17 12:15:56 +02:00
Ingo Molnar 23da766ab1 Linux 5.2-rc5 
-----BEGIN PGP SIGNATURE-----
 
 iQFSBAABCAA8FiEEq68RxlopcLEwq+PEeb4+QwBBGIYFAl0Gj1MeHHRvcnZhbGRz
 QGxpbnV4LWZvdW5kYXRpb24ub3JnAAoJEHm+PkMAQRiGctkH/0At3+SQPY2JJSy8
 i6+TDeytFx9OggeGLPHChRfehkAlvMb/kd34QHnuEvDqUuCAMU6HZQJFKoK9mvFI
 sDJVayPGDSqpm+iv8qLpMBPShiCXYVnGZeVfOdv36jUswL0k6wHV1pz4avFkDeZa
 1F4pmI6O2XRkNTYQawbUaFkAngWUCBG9ECLnHJnuIY6ohShBvjI4+E2JUaht+8gO
 M2h2b9ieddWmjxV3LTKgsK1v+347RljxdZTWnJ62SCDSEVZvsgSA9W2wnebVhBkJ
 drSmrFLxNiM+W45mkbUFmQixRSmjv++oRR096fxAnodBxMw0TDxE1RiMQWE6rVvG
 N6MC6xA=
 =+B0P
 -----END PGP SIGNATURE-----

Merge tag 'v5.2-rc5' into sched/core, to pick up fixes

Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-17 12:12:27 +02:00
Mauro Carvalho Chehab d6a3b24762 docs: scheduler: convert docs to ReST and rename to *.rst 
In order to prepare to add them to the Kernel API book,
convert the files to ReST format.

The conversion is actually:
  - add blank lines and identation in order to identify paragraphs;
  - fix tables markups;
  - add some lists markups;
  - mark literal blocks;
  - adjust title markups.

At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
 2019-06-14 14:32:18 -06:00
Thomas Gleixner b886d83c5b treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441 
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation version 2 of the license

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 315 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531190115.503150771@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 2019-06-05 17:37:17 +02:00
Dietmar Eggemann af75d1a9a9 sched/fair: Remove sgs->sum_weighted_load 
Since sg_lb_stats::sum_weighted_load is now identical with
sg_lb_stats::group_load remove it and replace its use case
(calculating load per task) with the latter.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rik van Riel <riel@surriel.com>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20190527062116.11512-7-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-03 11:49:41 +02:00
Dietmar Eggemann 0e1fef63d9 sched/core: Remove sd->*_idx 
The sched domain per rq load index files also disappear from the
/proc/sys/kernel/sched_domain/cpuX/domainY directories.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20190527062116.11512-6-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-03 11:49:40 +02:00
Dietmar Eggemann 55627e3cd2 sched/core: Remove rq->cpu_load[] 
The per rq load array values also disappear from the cpu#X sections in
/proc/sched_debug.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20190527062116.11512-5-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-03 11:49:40 +02:00
Dietmar Eggemann 3d8d535544 sched/debug: Remove sd->*_idx range on sysctl 
This reverts:

  commit 201c373e8e ("sched/debug: Limit sd->*_idx range on sysctl")

Load indexes (sd->*_idx) are no longer needed without rq->cpu_load[].
The range check for load indexes can be removed as well. Get rid of it
before the rq->cpu_load[] since it uses CPU_LOAD_IDX_MAX.

At the same time, fix the following coding style issues detected by
scripts/checkpatch.pl:

  ERROR: space prohibited before that ','
  ERROR: space prohibited before that close parenthesis ')'

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20190527062116.11512-4-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-03 11:49:39 +02:00
Dietmar Eggemann 1c1b8a7b03 sched/fair: Replace source_load() & target_load() with weighted_cpuload() 
With LB_BIAS disabled, source_load() & target_load() return
weighted_cpuload(). Replace both with calls to weighted_cpuload().

The function to obtain the load index (sd->*_idx) for an sd,
get_sd_load_idx(), can be removed as well.

Finally, get rid of the sched feature LB_BIAS.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20190527062116.11512-3-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-03 11:49:39 +02:00
Dietmar Eggemann 5e83eafbfd sched/fair: Remove the rq->cpu_load[] update code 
With LB_BIAS disabled, there is no need to update the rq->cpu_load[idx]
any more.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20190527062116.11512-2-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-03 11:49:38 +02:00
Dietmar Eggemann f2bedc4705 sched/fair: Remove rq->load 
The CFS class is the only one maintaining and using the CPU wide load
(rq->load(.weight)). The last use case of the CPU wide load in CFS's
set_next_entity() can be replaced by using the load of the CFS class
(rq->cfs.load(.weight)) instead.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190424084556.604-1-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-03 11:49:37 +02:00
Sebastian Andrzej Siewior 3bd3706251 sched/core: Provide a pointer to the valid CPU mask 
In commit:

  4b53a3412d ("sched/core: Remove the tsk_nr_cpus_allowed() wrapper")

the tsk_nr_cpus_allowed() wrapper was removed. There was not
much difference in !RT but in RT we used this to implement
migrate_disable(). Within a migrate_disable() section the CPU mask is
restricted to single CPU while the "normal" CPU mask remains untouched.

As an alternative implementation Ingo suggested to use:

	struct task_struct {
		const cpumask_t		*cpus_ptr;
		cpumask_t		cpus_mask;
        };
with
	t->cpus_ptr = &t->cpus_mask;

In -RT we then can switch the cpus_ptr to:

	t->cpus_ptr = &cpumask_of(task_cpu(p));

in a migration disabled region. The rules are simple:

 - Code that 'uses' ->cpus_allowed would use the pointer.
 - Code that 'modifies' ->cpus_allowed would use the direct mask.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190423142636.14347-1-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2019-06-03 11:49:37 +02:00
Thomas Gleixner c942fddf87 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157 
Based on 3 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version this program is distributed in the
  hope that it will be useful but without any warranty without even
  the implied warranty of merchantability or fitness for a particular
  purpose see the gnu general public license for more details

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version [author] [kishon] [vijay] [abraham]
  [i] [kishon]@[ti] [com] this program is distributed in the hope that
  it will be useful but without any warranty without even the implied
  warranty of merchantability or fitness for a particular purpose see
  the gnu general public license for more details

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version [author] [graeme] [gregory]
  [gg]@[slimlogic] [co] [uk] [author] [kishon] [vijay] [abraham] [i]
  [kishon]@[ti] [com] [based] [on] [twl6030]_[usb] [c] [author] [hema]
  [hk] [hemahk]@[ti] [com] this program is distributed in the hope
  that it will be useful but without any warranty without even the
  implied warranty of merchantability or fitness for a particular
  purpose see the gnu general public license for more details

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 1105 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.202006027@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 2019-05-30 11:26:37 -07:00
Thomas Gleixner 457c899653 treewide: Add SPDX license identifier for missed files 
Add SPDX license identifiers to all files which:

 - Have no license information of any form

 - Have EXPORT_.*_SYMBOL_GPL inside which was used in the
   initial scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 2019-05-21 10:50:45 +02:00
Dan Schatzberg df5ba5be74 kernel/sched/psi.c: expose pressure metrics on root cgroup 
Pressure metrics are already recorded and exposed in procfs for the
entire system, but any tool which monitors cgroup pressure has to
special case the root cgroup to read from procfs.  This patch exposes
the already recorded pressure metrics on the root cgroup.

Link: http://lkml.kernel.org/r/20190510174938.3361741-1-dschatzberg@fb.com
Signed-off-by: Dan Schatzberg <dschatzberg@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-05-14 19:52:48 -07:00
Suren Baghdasaryan 0e94682b73 psi: introduce psi monitor 
Psi monitor aims to provide a low-latency short-term pressure detection
mechanism configurable by users.  It allows users to monitor psi metrics
growth and trigger events whenever a metric raises above user-defined
threshold within user-defined time window.

Time window and threshold are both expressed in usecs.  Multiple psi
resources with different thresholds and window sizes can be monitored
concurrently.

Psi monitors activate when system enters stall state for the monitored
psi metric and deactivate upon exit from the stall state.  While system
is in the stall state psi signal growth is monitored at a rate of 10
times per tracking window.  Min window size is 500ms, therefore the min
monitoring interval is 50ms.  Max window size is 10s with monitoring
interval of 1s.

When activated psi monitor stays active for at least the duration of one
tracking window to avoid repeated activations/deactivations when psi
signal is bouncing.

Notifications to the users are rate-limited to one per tracking window.

Link: http://lkml.kernel.org/r/20190319235619.260832-8-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-05-14 19:52:48 -07:00