From: David Carlier <devnexen@gmail.com>
To: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Valentin Schneider <vschneid@redhat.com>,
K Prateek Nayak <kprateek.nayak@amd.com>
Cc: David Carlier <devnexen@gmail.com>, linux-kernel@vger.kernel.org
Subject: [PATCH] sched/rt: Use atomic_try_cmpxchg_acquire() in rto_start_trylock()
Date: Wed, 15 Apr 2026 13:40:44 +0100 [thread overview]
Message-ID: <20260415124045.372307-1-devnexen@gmail.com> (raw)
Replace this pattern in rto_start_trylock():
!atomic_cmpxchg_acquire(*ptr, 0, new)
... with the simpler and faster:
atomic_try_cmpxchg_acquire(*ptr, &zero, new)
The x86 CMPXCHG instruction returns success in the ZF flag, so
atomic_try_cmpxchg_acquire() saves a compare after the CMPXCHG.
No functional change intended.
Signed-off-by: David Carlier <devnexen@gmail.com>
---
kernel/sched/rt.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 4ee8faf01441..13ac94899c18 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2172,7 +2172,8 @@ static int rto_next_cpu(struct root_domain *rd)
static inline bool rto_start_trylock(atomic_t *v)
{
- return !atomic_cmpxchg_acquire(v, 0, 1);
+ int zero = 0;
+ return atomic_try_cmpxchg_acquire(v, &zero, 1);
}
static inline void rto_start_unlock(atomic_t *v)
--
2.53.0
next reply other threads:[~2026-04-15 12:40 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-15 12:40 David Carlier [this message]
2026-04-15 18:14 ` [PATCH] sched/rt: Use atomic_try_cmpxchg_acquire() in rto_start_trylock() Uros Bizjak
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