mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-12 05:48:40 +00:00
![]() A long-tail load balance cost is observed on the newly idle path, this is caused by a race window between the first nr_running check of the busiest runqueue and its nr_running recheck in detach_tasks. Before the busiest runqueue is locked, the tasks on the busiest runqueue could be pulled by other CPUs and nr_running of the busiest runqueu becomes 1 or even 0 if the running task becomes idle, this causes detach_tasks breaks with LBF_ALL_PINNED flag set, and triggers load_balance redo at the same sched_domain level. In order to find the new busiest sched_group and CPU, load balance will recompute and update the various load statistics, which eventually leads to the long-tail load balance cost. This patch clears LBF_ALL_PINNED flag for this race condition, and hence reduces the long-tail cost of newly idle balance. Signed-off-by: Aubrey Li <aubrey.li@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org> Link: https://lkml.kernel.org/r/1614154549-116078-1-git-send-email-aubrey.li@intel.com |
||
---|---|---|
.. | ||
autogroup.c | ||
autogroup.h | ||
clock.c | ||
completion.c | ||
core.c | ||
cpuacct.c | ||
cpudeadline.c | ||
cpudeadline.h | ||
cpufreq.c | ||
cpufreq_schedutil.c | ||
cpupri.c | ||
cpupri.h | ||
cputime.c | ||
deadline.c | ||
debug.c | ||
fair.c | ||
features.h | ||
idle.c | ||
isolation.c | ||
loadavg.c | ||
Makefile | ||
membarrier.c | ||
pelt.c | ||
pelt.h | ||
psi.c | ||
rt.c | ||
sched-pelt.h | ||
sched.h | ||
smp.h | ||
stats.c | ||
stats.h | ||
stop_task.c | ||
swait.c | ||
topology.c | ||
wait.c | ||
wait_bit.c |