diff options
author | Peter Zijlstra <peterz@infradead.org> | 2020-05-24 21:29:55 +0100 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2020-05-25 07:01:44 +0200 |
commit | c6e7bd7afaeb3af55ffac122828035f1c01d1d7b (patch) | |
tree | f1e77c6930f4ead3cfb4e231fd5fede2779b1cf5 /kernel/sched/sched.h | |
parent | d505b8af58912ae1e1a211fabc9995b19bd40828 (diff) | |
download | linux-c6e7bd7afaeb3af55ffac122828035f1c01d1d7b.tar.bz2 |
sched/core: Optimize ttwu() spinning on p->on_cpu
Both Rik and Mel reported seeing ttwu() spend significant time on:
smp_cond_load_acquire(&p->on_cpu, !VAL);
Attempt to avoid this by queueing the wakeup on the CPU that owns the
p->on_cpu value. This will then allow the ttwu() to complete without
further waiting.
Since we run schedule() with interrupts disabled, the IPI is
guaranteed to happen after p->on_cpu is cleared, this is what makes it
safe to queue early.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Jirka Hladky <jhladky@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: valentin.schneider@arm.com
Cc: Hillf Danton <hdanton@sina.com>
Cc: Rik van Riel <riel@surriel.com>
Link: https://lore.kernel.org/r/20200524202956.27665-2-mgorman@techsingularity.net
Diffstat (limited to 'kernel/sched/sched.h')
0 files changed, 0 insertions, 0 deletions