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sched/fair: use try_cmpxchg in task_numa_work

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Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in
task_numa_work.  x86 CMPXCHG instruction returns success in ZF flag, so
this change saves a compare after cmpxchg (and related move instruction in
front of cmpxchg).

No functional change intended.

Link: https://lkml.kernel.org/r/20220822173956.82525-1-ubizjak@gmail.com
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Uros Bizjak 2022-08-22 19:39:56 +02:00 committed by Andrew Morton
parent 333d073dee
commit 8baceabca6
1 changed files with 1 additions and 1 deletions
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2
kernel/sched/fair.c
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@ -2964,7 +2964,7 @@ static void task_numa_work(struct callback_head *work)
}
next_scan = now + msecs_to_jiffies(p->numa_scan_period);
if (cmpxchg(&mm->numa_next_scan, migrate, next_scan) != migrate)
if (!try_cmpxchg(&mm->numa_next_scan, &migrate, next_scan))
return;
/*