linux_old1/kernel/sched
Ying Huang 966a967116 smp: Avoid using two cache lines for struct call_single_data
struct call_single_data is used in IPIs to transfer information between
CPUs.  Its size is bigger than sizeof(unsigned long) and less than
cache line size.  Currently it is not allocated with any explicit alignment
requirements.  This makes it possible for allocated call_single_data to
cross two cache lines, which results in double the number of the cache lines
that need to be transferred among CPUs.

This can be fixed by requiring call_single_data to be aligned with the
size of call_single_data. Currently the size of call_single_data is the
power of 2.  If we add new fields to call_single_data, we may need to
add padding to make sure the size of new definition is the power of 2
as well.

Fortunately, this is enforced by GCC, which will report bad sizes.

To set alignment requirements of call_single_data to the size of
call_single_data, a struct definition and a typedef is used.

To test the effect of the patch, I used the vm-scalability multiple
thread swap test case (swap-w-seq-mt).  The test will create multiple
threads and each thread will eat memory until all RAM and part of swap
is used, so that huge number of IPIs are triggered when unmapping
memory.  In the test, the throughput of memory writing improves ~5%
compared with misaligned call_single_data, because of faster IPIs.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Huang, Ying <ying.huang@intel.com>
[ Add call_single_data_t and align with size of call_single_data. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/87bmnqd6lz.fsf@yhuang-mobile.sh.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-29 15:14:38 +02:00
..
Makefile Merge branch 'WIP.sched/core' into sched/core 2017-06-20 12:28:21 +02:00
autogroup.c sched/autogroup: Rename auto_group.[ch] to autogroup.[ch] 2017-02-08 09:01:11 +01:00
autogroup.h sched/headers: Prepare for new header dependencies before moving code to <linux/sched/autogroup.h> 2017-03-02 08:42:28 +01:00
clock.c sched/clock: Fix early boot preempt assumption in __set_sched_clock_stable() 2017-05-24 09:10:00 +02:00
completion.c locking/lockdep: Apply crossrelease to completions 2017-08-10 12:29:10 +02:00
core.c locking: Introduce smp_mb__after_spinlock() 2017-08-10 12:29:02 +02:00
cpuacct.c sched/cputime: Convert kcpustat to nsecs 2017-02-01 09:13:47 +01:00
cpuacct.h sched/cpuacct: Simplify the cpuacct code 2016-03-21 11:00:28 +01:00
cpudeadline.c sched/core: Remove the tsk_cpus_allowed() wrapper 2017-03-02 08:42:24 +01:00
cpudeadline.h sched/deadline: Split cpudl_set() into cpudl_set() and cpudl_clear() 2016-09-05 13:29:43 +02:00
cpufreq.c cpufreq / sched: Pass flags to cpufreq_update_util() 2016-08-16 22:14:55 +02:00
cpufreq_schedutil.c cpufreq: schedutil: Fix sugov_start() versus sugov_update_shared() race 2017-07-12 14:47:48 +02:00
cpupri.c sched/core: Remove the tsk_cpus_allowed() wrapper 2017-03-02 08:42:24 +01:00
cpupri.h sched/cpupri: Remove unnecessary definitions in cpupri.h 2014-11-16 10:58:59 +01:00
cputime.c sched/cputime: Don't use smp_processor_id() in preemptible context 2017-07-14 10:27:15 +02:00
deadline.c sched/deadline: Fix confusing comments about selection of top pi-waiter 2017-07-14 10:35:16 +02:00
debug.c sched/debug: Expose the number of RT/DL tasks that can migrate 2017-06-30 09:32:07 +02:00
fair.c sched/fair: Fix load_balance() affinity redo path 2017-07-05 16:28:48 +02:00
features.h sched/core: Implement new approach to scale select_idle_cpu() 2017-06-08 10:25:17 +02:00
idle.c sched/idle: Add deferrable vmstat_updater back 2017-06-08 10:32:09 +02:00
idle_task.c sched/core: Add wrappers for lockdep_(un)pin_lock() 2017-01-14 11:29:30 +01:00
loadavg.c sched/loadavg: Generalize "_idle" naming to "_nohz" 2017-06-22 11:30:01 +02:00
rt.c sched/rt: Move RT related code from sched/core.c to sched/rt.c 2017-06-23 10:46:45 +02:00
sched-pelt.h sched/fair: Move the PELT constants into a generated header 2017-04-14 10:26:37 +02:00
sched.h smp: Avoid using two cache lines for struct call_single_data 2017-08-29 15:14:38 +02:00
stats.c sched: use %*pb[l] to print bitmaps including cpumasks and nodemasks 2015-02-13 21:21:37 -08:00
stats.h sched/headers: Move cputime functionality from <linux/sched.h> and <linux/cputime.h> into <linux/sched/cputime.h> 2017-03-03 01:45:22 +01:00
stop_task.c sched/core: Add wrappers for lockdep_(un)pin_lock() 2017-01-14 11:29:30 +01:00
swait.c sched/wait: Remove the lockless swait_active() check in swake_up*() 2017-08-10 12:28:53 +02:00
topology.c sched/topology: Rename sched_group_cpus() 2017-05-15 10:15:34 +02:00
wait.c sched/wait: Disambiguate wq_entry->task_list and wq_head->task_list naming 2017-06-20 12:19:14 +02:00
wait_bit.c sched/wait: Disambiguate wq_entry->task_list and wq_head->task_list naming 2017-06-20 12:19:14 +02:00