kernel_optimize_test/kernel/sched
Qais Yousef 91e10f2ad1 sched/eas: Don't update misfit status if the task is pinned
[ Upstream commit 0ae78eec8aa64e645866e75005162603a77a0f49 ]

If the task is pinned to a cpu, setting the misfit status means that
we'll unnecessarily continuously attempt to migrate the task but fail.

This continuous failure will cause the balance_interval to increase to
a high value, and eventually cause unnecessary significant delays in
balancing the system when real imbalance happens.

Caught while testing uclamp where rt-app calibration loop was pinned to
cpu 0, shortly after which we spawn another task with high util_clamp
value. The task was failing to migrate after over 40ms of runtime due to
balance_interval unnecessary expanded to a very high value from the
calibration loop.

Not done here, but it could be useful to extend the check for pinning to
verify that the affinity of the task has a cpu that fits. We could end
up in a similar situation otherwise.

Fixes: 3b1baa6496 ("sched/fair: Add 'group_misfit_task' load-balance type")
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Quentin Perret <qperret@google.com>
Acked-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20210119120755.2425264-1-qais.yousef@arm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-03-04 11:37:44 +01:00
..
autogroup.c
autogroup.h
clock.c
completion.c
core.c sched: Reenable interrupts in do_sched_yield() 2020-12-30 11:52:59 +01:00
cpuacct.c
cpudeadline.c
cpudeadline.h
cpufreq_schedutil.c cpufreq: Introduce governor flags 2020-11-10 18:31:17 +01:00
cpufreq.c
cpupri.c
cpupri.h
cputime.c
deadline.c sched/deadline: Fix sched_dl_global_validate() 2020-12-30 11:52:59 +01:00
debug.c sched/debug: Fix memory corruption caused by multiple small reads of flags 2020-11-10 18:38:49 +01:00
fair.c sched/eas: Don't update misfit status if the task is pinned 2021-03-04 11:37:44 +01:00
features.h
idle.c sched/idle: Fix arch_cpu_idle() vs tracing 2020-11-24 16:47:35 +01:00
isolation.c
loadavg.c
Makefile
membarrier.c membarrier: Execute SYNC_CORE on the calling thread 2020-12-09 09:37:43 +01:00
pelt.c
pelt.h
psi.c
rt.c treewide: Convert macro and uses of __section(foo) to __section("foo") 2020-10-25 14:51:49 -07:00
sched-pelt.h
sched.h sched/deadline: Fix sched_dl_global_validate() 2020-12-30 11:52:59 +01:00
smp.h
stats.c
stats.h
stop_task.c treewide: Convert macro and uses of __section(foo) to __section("foo") 2020-10-25 14:51:49 -07:00
swait.c
topology.c
wait_bit.c
wait.c