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linux-stable/kernel/sched
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Srikar Dronamraju 1f621e028b sched/fair: Fix asym packing to select correct CPU 
When asymmetric packing is set in the sched_domain and target CPU is
busy, update_sd_pick_busiest() may not select the busiest runqueue.
When target CPU is busy, find_busiest_group() will ignore checks for
asym packing and may continue to load balance using the currently
selected not-the-busiest runqueue as source runqueue.
Selecting the busiest runqueue as source when the target CPU is busy,
should result in achieving much better load balance.

Also when target CPU is not busy and asymmetric packing is set in sd,
select higher CPU as source CPU for load balancing.

While doing this change, move the check to see if target CPU is busy
into check_asym_packing().

The extent of performance benefit from this change decreases with the
increasing load. However there is benefit in undercommit as well as
overcommit conditions.

1. Record per second ebizzy (32 threads) on a 64 CPU power 7 box. (5 iterations)
4.6.0-rc2
	Testcase:         Min         Max         Avg      StdDev
	  ebizzy:  5223767.00 10368236.00  7946971.00  1753094.76

4.6.0-rc2+asym-changes
	Testcase:         Min         Max         Avg      StdDev     %Change
	  ebizzy:  8617191.00 13872356.00 11383980.00  1783400.89     +24.78%

2. Record per second ebizzy (64 threads) on a 64 CPU power 7 box. (5 iterations)
4.6.0-rc2
	Testcase:         Min         Max         Avg      StdDev
	  ebizzy:  6497666.00 18399783.00 10818093.20  4051452.08

4.6.0-rc2+asym-changes
	Testcase:         Min         Max         Avg      StdDev     %Change
	  ebizzy:  7567365.00 19456937.00 11674063.60  4295407.48      +4.40%

3. Record per second ebizzy (128 threads) on a 64 CPU power 7 box. (5 iterations)
4.6.0-rc2
	Testcase:         Min         Max         Avg      StdDev
	  ebizzy: 37073983.00 40341911.00 38776241.80  1259766.82

4.6.0-rc2+asym-changes
	Testcase:         Min         Max         Avg      StdDev     %Change
	  ebizzy: 38030399.00 41333378.00 39827404.40  1255001.86      +2.54%

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Gautham R Shenoy <ego@linux.vnet.ibm.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1459948660-16073-1-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-23 14:20:35 +02:00
..
auto_group.c sched/core: Move the sched_to_prio[] arrays out of line 2015-12-04 10:34:46 +01:00
auto_group.h sched, timer: Convert usages of ACCESS_ONCE() in the scheduler to READ_ONCE()/WRITE_ONCE() 2015-05-08 12:11:32 +02:00
clock.c sched/clock: Make local_clock()/cpu_clock() inline 2016-04-13 12:25:22 +02:00
completion.c sched/completion: Serialize completion_done() with complete() 2015-02-18 14:27:40 +01:00
core.c sched/debug: Don't dump sched debug info in SysRq-W 2016-04-13 11:23:21 +02:00
cpuacct.c sched/cpuacct: Check for NULL when using task_pt_regs() 2016-04-13 13:22:37 +02:00
cpuacct.h sched/cpuacct: Simplify the cpuacct code 2016-03-21 11:00:28 +01:00
cpudeadline.c sched/deadline: Unify dl_time_before() usage 2015-09-23 09:51:25 +02:00
cpudeadline.h sched/deadline: Unify dl_time_before() usage 2015-09-23 09:51:25 +02:00
cpufreq.c cpufreq: Move scheduler-related code to the sched directory 2016-03-10 20:44:47 +01:00
cpupri.c Merge commit '3cf2f34' into sched/core, to fix build error 2014-06-12 13:46:37 +02:00
cpupri.h sched/cpupri: Remove unnecessary definitions in cpupri.h 2014-11-16 10:58:59 +01:00
cputime.c sched/cputime: Fix steal_account_process_tick() to always return jiffies 2016-03-08 12:24:56 +01:00
deadline.c Power management and ACPI material for v4.6-rc1, part 1 2016-03-16 14:10:53 -07:00
debug.c sched/debug: Add deadline scheduler bandwidth ratio to /proc/sched_debug 2016-02-29 09:53:07 +01:00
fair.c sched/fair: Fix asym packing to select correct CPU 2016-04-23 14:20:35 +02:00
features.h sched/fair: Convert arch_scale_cpu_capacity() from weak function to #define 2015-09-13 09:52:55 +02:00
idle.c rcu: Make CPU_DYING_IDLE an explicit call 2016-03-01 20:36:58 +01:00
idle_task.c sched/fair: Remove empty idle enter and exit functions 2015-11-23 09:37:51 +01:00
loadavg.c sched: Move the loadavg code to a more obvious location 2015-05-08 12:04:12 +02:00
Makefile kernel: add kcov code coverage 2016-03-22 15:36:02 -07:00
rt.c Power management and ACPI material for v4.6-rc1, part 1 2016-03-16 14:10:53 -07:00
sched.h sched/fair: Initiate a new task's util avg to a bounded value 2016-03-31 10:49:46 +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/debug: Make schedstats a runtime tunable that is disabled by default 2016-02-09 11:54:23 +01:00
stop_task.c sched: Make sched_class::set_cpus_allowed() unconditional 2015-08-12 12:06:09 +02:00
swait.c wait.[ch]: Introduce the simple waitqueue (swait) implementation 2016-02-25 11:27:16 +01:00
wait.c sched/wait: Fix the signal handling fix 2015-12-13 14:30:59 -08:00