linux/kernel/sched
Jason Low 8236d907ab sched: Reduce contention in update_cfs_rq_blocked_load()
When running workloads on 2+ socket systems, based on perf profiles, the
update_cfs_rq_blocked_load() function often shows up as taking up a
noticeable % of run time.

Much of the contention is in __update_cfs_rq_tg_load_contrib() when we
update the tg load contribution stats.  However, it turns out that in many
cases, they don't need to be updated and "tg_contrib" is 0.

This patch adds a check in __update_cfs_rq_tg_load_contrib() to skip updating
tg load contribution stats when nothing needs to be updated. This reduces the
cacheline contention that would be unnecessary.

Reviewed-by: Ben Segall <bsegall@google.com>
Reviewed-by: Waiman Long <Waiman.Long@hp.com>
Signed-off-by: Jason Low <jason.low2@hp.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Turner <pjt@google.com>
Cc: jason.low2@hp.com
Cc: Yuyang Du <yuyang.du@intel.com>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: Chegu Vinod <chegu_vinod@hp.com>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1409643684.19197.15.camel@j-VirtualBox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-09 06:47:29 +02:00
..
auto_group.c sched: Change autogroup_move_group() to use for_each_thread() 2014-08-20 09:47:18 +02:00
auto_group.h Revert "sched/autogroup: Fix crash on reboot when autogroup is disabled" 2012-12-11 10:23:45 +01:00
clock.c kernel: use macros from compiler.h instead of __attribute__((...)) 2014-04-07 16:36:11 -07:00
completion.c sched: Move completion code from core.c to completion.c 2013-11-06 07:49:19 +01:00
core.c sched: Migrate waking tasks 2014-09-09 06:47:27 +02:00
cpuacct.c cgroup: rename cgroup_subsys->base_cftypes to ->legacy_cftypes 2014-07-15 11:05:09 -04:00
cpuacct.h sched/cpuacct: Initialize root cpuacct earlier 2013-04-10 13:54:20 +02:00
cpudeadline.c sched/deadline: Replace NR_CPUS arrays 2014-05-22 10:21:28 +02:00
cpudeadline.h sched/deadline: Replace NR_CPUS arrays 2014-05-22 10:21:28 +02:00
cpupri.c Merge commit '3cf2f34' into sched/core, to fix build error 2014-06-12 13:46:37 +02:00
cpupri.h sched/cpupri: Replace NR_CPUS arrays 2014-05-22 10:21:29 +02:00
cputime.c sched, time: Atomically increment stime & utime 2014-09-08 08:17:02 +02:00
deadline.c sched/deadline: Fix a precision problem in the microseconds range 2014-09-07 11:09:59 +02:00
debug.c sched: s/do_each_thread/for_each_process_thread/ in debug.c 2014-08-20 09:47:17 +02:00
fair.c sched: Reduce contention in update_cfs_rq_blocked_load() 2014-09-09 06:47:29 +02:00
features.h sched: Rename capacity related flags 2014-06-05 11:52:32 +02:00
idle_task.c sched: Transform resched_task() into resched_curr() 2014-07-16 13:38:19 +02:00
idle.c ACPI and power management updates for 3.17-rc1 2014-08-06 20:34:19 -07:00
Makefile sched/idle: Move cpu/idle.c to sched/idle.c 2014-02-11 09:58:30 +01:00
proc.c cpuidle: menu: Lookup CPU runqueues less 2014-08-06 21:17:45 +02:00
rt.c sched: Add wrapper for checking task_struct::on_rq 2014-08-20 14:52:59 +02:00
sched.h sched: Teach scheduler to understand TASK_ON_RQ_MIGRATING state 2014-08-20 14:53:00 +02:00
stats.c kernel: audit/fix non-modular users of module_init in core code 2014-04-03 16:21:07 -07:00
stats.h sched: Micro-optimize by dropping unnecessary task_rq() calls 2013-09-25 13:51:06 +02:00
stop_task.c sched: Add wrapper for checking task_struct::on_rq 2014-08-20 14:52:59 +02:00
wait.c sched: Allow wait_on_bit_action() functions to support a timeout 2014-07-16 15:10:41 +02:00