percpu_ida() decouples disabling interrupts from the locking operations.
This breaks some assumptions if the locking operations are replaced like
they are under -RT.
The same locking can be achieved by avoiding local_irq_save() and using
spin_lock_irqsave() instead. percpu_ida_alloc() gains one more preemption
point because after unlocking the fastpath and before the pool lock is
acquired, the interrupts are briefly enabled.
Link: http://lkml.kernel.org/r/20180504153218.7301-1-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Nicholas Bellinger <nab@linux-iscsi.org>
Cc: Shaohua Li <shli@fb.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
<linux/topology.h> is still needed - also update other headers
and .c files that depend on sched.h including gfp.h (and its
sub-headers) for them.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fix up affected files that include this signal functionality via sched.h.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
__GFP_WAIT was used to signal that the caller was in atomic context and
could not sleep. Now it is possible to distinguish between true atomic
context and callers that are not willing to sleep. The latter should
clear __GFP_DIRECT_RECLAIM so kswapd will still wake. As clearing
__GFP_WAIT behaves differently, there is a risk that people will clear the
wrong flags. This patch renames __GFP_WAIT to __GFP_RECLAIM to clearly
indicate what it does -- setting it allows all reclaim activity, clearing
them prevents it.
[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
These three #includes seem to be completely redundant: Removing them
yields identical objdump -d output for each of {allyes,allno,def}config,
and neither included file end up in the generated dependency file through
some recursive include. In total, about 50 lines are eliminated from
.percpu.o.cmd.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull block IO fixes from Jens Axboe:
"Second round of updates and fixes for 3.14-rc2. Most of this stuff
has been queued up for a while. The notable exception is the blk-mq
changes, which are naturally a bit more in flux still.
The pull request contains:
- Two bug fixes for the new immutable vecs, causing crashes with raid
or swap. From Kent.
- Various blk-mq tweaks and fixes from Christoph. A fix for
integrity bio's from Nic.
- A few bcache fixes from Kent and Darrick Wong.
- xen-blk{front,back} fixes from David Vrabel, Matt Rushton, Nicolas
Swenson, and Roger Pau Monne.
- Fix for a vec miscount with integrity vectors from Martin.
- Minor annotations or fixes from Masanari Iida and Rashika Kheria.
- Tweak to null_blk to do more normal FIFO processing of requests
from Shlomo Pongratz.
- Elevator switching bypass fix from Tejun.
- Softlockup in blkdev_issue_discard() fix when !CONFIG_PREEMPT from
me"
* 'for-linus' of git://git.kernel.dk/linux-block: (31 commits)
block: add cond_resched() to potentially long running ioctl discard loop
xen-blkback: init persistent_purge_work work_struct
blk-mq: pair blk_mq_start_request / blk_mq_requeue_request
blk-mq: dont assume rq->errors is set when returning an error from ->queue_rq
block: Fix cloning of discard/write same bios
block: Fix type mismatch in ssize_t_blk_mq_tag_sysfs_show
blk-mq: rework flush sequencing logic
null_blk: use blk_complete_request and blk_mq_complete_request
virtio_blk: use blk_mq_complete_request
blk-mq: rework I/O completions
fs: Add prototype declaration to appropriate header file include/linux/bio.h
fs: Mark function as static in fs/bio-integrity.c
block/null_blk: Fix completion processing from LIFO to FIFO
block: Explicitly handle discard/write same segments
block: Fix nr_vecs for inline integrity vectors
blk-mq: Add bio_integrity setup to blk_mq_make_request
blk-mq: initialize sg_reserved_size
blk-mq: handle dma_drain_size
blk-mq: divert __blk_put_request for MQ ops
blk-mq: support at_head inserations for blk_execute_rq
...
steal_tags only happens when free tags is more than half of the total
tags. This is too strict and can cause live lock. I found that if one
cpu has free tags, but other cpu can't steal (thread is bound to
specific cpus), threads which want to allocate tags are always
sleeping. I found this when I run next patch, but this could happen
without it I think.
I did performance test too with null_blk. Two cases (each cpu has enough
percpu tags, or total tags are limited), no performance changes were
observed.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This patch addresses a bug where connection reset would hang
indefinately once percpu_ida_alloc() was starved for tags, due
to the fact that it always assumed uninterruptible sleep mode.
So now make percpu_ida_alloc() check for signal_pending_state() for
making interruptible sleep optional, and convert iscsit_allocate_cmd()
to set TASK_INTERRUPTIBLE for GFP_KERNEL, or TASK_RUNNING for
GFP_ATOMIC.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Kent Overstreet <kmo@daterainc.com>
Cc: <stable@vger.kernel.org> #3.12+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This patch changes percpu_ida_alloc() + callers to accept task state
bitmask for prepare_to_wait() for code like target/iscsi that needs
it for interruptible sleep, that is provided in a subsequent patch.
It now expects TASK_UNINTERRUPTIBLE when the caller is able to sleep
waiting for a new tag, or TASK_RUNNING when the caller cannot sleep,
and is forced to return a negative value when no tags are available.
v2 changes:
- Include blk-mq + tcm_fc + vhost/scsi + target/iscsi changes
- Drop signal_pending_state() call
v3 changes:
- Only call prepare_to_wait() + finish_wait() when != TASK_RUNNING
(PeterZ)
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: <stable@vger.kernel.org> #3.12+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Pull SCSI target updates from Nicholas Bellinger:
"Things have been quiet this round with mostly bugfixes, percpu
conversions, and other minor iscsi-target conformance testing changes.
The highlights include:
- Add demo_mode_discovery attribute for iscsi-target (Thomas)
- Convert tcm_fc(FCoE) to use percpu-ida pre-allocation
- Add send completion interrupt coalescing for ib_isert
- Convert target-core to use percpu-refcounting for se_lun
- Fix mutex_trylock usage bug in iscsit_increment_maxcmdsn
- tcm_loop updates (Hannes)
- target-core ALUA cleanups + prep for v3.14 SCSI Referrals support (Hannes)
v3.14 is currently shaping to be a busy development cycle in target
land, with initial support for T10 Referrals and T10 DIF currently on
the roadmap"
* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending: (40 commits)
iscsi-target: chap auth shouldn't match username with trailing garbage
iscsi-target: fix extract_param to handle buffer length corner case
iscsi-target: Expose default_erl as TPG attribute
target_core_configfs: split up ALUA supported states
target_core_alua: Make supported states configurable
target_core_alua: Store supported ALUA states
target_core_alua: Rename ALUA_ACCESS_STATE_OPTIMIZED
target_core_alua: spellcheck
target core: rename (ex,im)plict -> (ex,im)plicit
percpu-refcount: Add percpu-refcount.o to obj-y
iscsi-target: Do not reject non-immediate CmdSNs exceeding MaxCmdSN
iscsi-target: Convert iscsi_session statistics to atomic_long_t
target: Convert se_device statistics to atomic_long_t
target: Fix delayed Task Aborted Status (TAS) handling bug
iscsi-target: Reject unsupported multi PDU text command sequence
ib_isert: Avoid duplicate iscsit_increment_maxcmdsn call
iscsi-target: Fix mutex_trylock usage in iscsit_increment_maxcmdsn
target: Core does not need blkdev.h
target: Pass through I/O topology for block backstores
iser-target: Avoid using FRMR for single dma entry requests
...
Add an API to return free tags, blk-mq-tag will use it.
Note, this just returns a snapshot of free tags number. blk-mq-tag has
two usages of it. One is for info output for diagnosis. The other is to
quickly check if there are free tags for request dispatch checking.
Neither requires very precise.
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a new API to iterate free ids. blk-mq-tag will use it.
Note, this doesn't guarantee to iterate all free ids restrictly. Caller
should be aware of this. blk-mq uses it to do sanity check for request
timedout, so can tolerate the limitation.
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Make percpu_ida percpu size/batch configurable. The block-mq-tag will
use it.
After block-mq uses percpu_ida to manage tags, performance is improved.
My test is done in a 2 sockets machine, 12 process cross the 2 sockets.
So if there is lock contention or ipi, should be stressed heavily.
Testing is done for null-blk.
hw_queue_depth nopatch iops patch iops
64 ~800k/s ~1470k/s
2048 ~4470k/s ~4340k/s
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Removing unused struct percpu_ida *pool from arguements of
alloc_local_tag, changed it's one use in percpu_ida.c
(nab: Fixed reference of idr.c -> percpu_ida.c)
Signed-Off-By: Nick Swenson <nks@daterainc.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Percpu frontend for allocating ids. With percpu allocation (that works),
it's impossible to guarantee it will always be possible to allocate all
nr_tags - typically, some will be stuck on a remote percpu freelist
where the current job can't get to them.
We do guarantee that it will always be possible to allocate at least
(nr_tags / 2) tags - this is done by keeping track of which and how many
cpus have tags on their percpu freelists. On allocation failure if
enough cpus have tags that there could potentially be (nr_tags / 2) tags
stuck on remote percpu freelists, we then pick a remote cpu at random to
steal from.
Note that there's no cpu hotplug notifier - we don't care, because
steal_tags() will eventually get the down cpu's tags. We _could_ satisfy
more allocations if we had a notifier - but we'll still meet our
guarantees and it's absolutely not a correctness issue, so I don't think
it's worth the extra code.
From akpm:
"It looks OK to me (that's as close as I get to an ack :))
v6 changes:
- Add #include <linux/cpumask.h> to include/linux/percpu_ida.h to
make alpha/arc builds happy (Fengguang)
- Move second (cpu >= nr_cpu_ids) check inside of first check scope
in steal_tags() (akpm + nab)
v5 changes:
- Change percpu_ida->cpus_have_tags to cpumask_t (kmo + akpm)
- Add comment for percpu_ida_cpu->lock + ->nr_free (kmo + akpm)
- Convert steal_tags() to use cpumask_weight() + cpumask_next() +
cpumask_first() + cpumask_clear_cpu() (kmo + akpm)
- Add comment for alloc_global_tags() (kmo + akpm)
- Convert percpu_ida_alloc() to use cpumask_set_cpu() (kmo + akpm)
- Convert percpu_ida_free() to use cpumask_set_cpu() (kmo + akpm)
- Drop percpu_ida->cpus_have_tags allocation in percpu_ida_init()
(kmo + akpm)
- Drop percpu_ida->cpus_have_tags kfree in percpu_ida_destroy()
(kmo + akpm)
- Add comment for percpu_ida_alloc @ gfp (kmo + akpm)
- Move to percpu_ida.c + percpu_ida.h (kmo + akpm + nab)
v4 changes:
- Fix tags.c reference in percpu_ida_init (akpm)
Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Nicholas A. Bellinger" <nab@linux-iscsi.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Sebastian Andrzej Siewior