Messages in this thread Patch in this message | | | Date | Thu, 19 May 2022 21:49:51 -0000 | From | "tip-bot2 for Uros Bizjak" <> | Subject | [tip: locking/core] sched/clock: Use try_cmpxchg64 in sched_clock_{local,remote} |
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The following commit has been merged into the locking/core branch of tip:
Commit-ID: 8491d1bdf5de152f27fc941e2dcdc4e66c950542 Gitweb: https://git.kernel.org/tip/8491d1bdf5de152f27fc941e2dcdc4e66c950542 Author: Uros Bizjak <ubizjak@gmail.com> AuthorDate: Wed, 18 May 2022 20:49:53 +02:00 Committer: Peter Zijlstra <peterz@infradead.org> CommitterDate: Thu, 19 May 2022 23:46:09 +02:00
sched/clock: Use try_cmpxchg64 in sched_clock_{local,remote}
Use try_cmpxchg64 instead of cmpxchg64 (*ptr, old, new) != old in sched_clock_{local,remote}. x86 cmpxchg returns success in ZF flag, so this change saves a compare after cmpxchg (and related move instruction in front of cmpxchg).
Signed-off-by: Uros Bizjak <ubizjak@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220518184953.3446778-1-ubizjak@gmail.com --- kernel/sched/clock.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c index d9272d9..e374c0c 100644 --- a/kernel/sched/clock.c +++ b/kernel/sched/clock.c @@ -287,7 +287,7 @@ again: clock = wrap_max(clock, min_clock); clock = wrap_min(clock, max_clock); - if (cmpxchg64(&scd->clock, old_clock, clock) != old_clock) + if (!try_cmpxchg64(&scd->clock, &old_clock, clock)) goto again; return clock; @@ -349,7 +349,7 @@ again: val = remote_clock; } - if (cmpxchg64(ptr, old_val, val) != old_val) + if (!try_cmpxchg64(ptr, &old_val, val)) goto again; return val;
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