From: Frederic Weisbecker <fweisbec@gmail.com>
To: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <peterz@infradead.org>,
Paul Mackerras <paulus@samba.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/3] perf_event: cleanup for cpu_clock_perf_event_update()
Date: Wed, 9 Dec 2009 09:54:19 +0100 [thread overview]
Message-ID: <20091209085417.GC5152@nowhere> (raw)
In-Reply-To: <4B1F19DC.90204@cn.fujitsu.com>
On Wed, Dec 09, 2009 at 11:30:36AM +0800, Xiao Guangrong wrote:
> Using atomic64_xchg() instead of atomic64_read() and atomic64_set().
>
> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
> ---
> kernel/perf_event.c | 3 +--
> 1 files changed, 1 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/perf_event.c b/kernel/perf_event.c
> index 592b293..8f46012 100644
> --- a/kernel/perf_event.c
> +++ b/kernel/perf_event.c
> @@ -4079,8 +4079,7 @@ static void cpu_clock_perf_event_update(struct perf_event *event)
> u64 now;
>
> now = cpu_clock(cpu);
> - prev = atomic64_read(&event->hw.prev_count);
> - atomic64_set(&event->hw.prev_count, now);
> + prev = atomic64_xchg(&event->hw.prev_count, now);
> atomic64_add(now - prev, &event->count);
> }
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
next prev parent reply other threads:[~2009-12-09 8:54 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-09 3:28 [PATCH 1/3] perf_event: cleanup for __perf_event_init_context() Xiao Guangrong
2009-12-09 3:29 ` [PATCH 2/3] perf_event: allocate children's perf_event_ctxp at the right time Xiao Guangrong
2009-12-09 3:30 ` [PATCH 3/3] perf_event: cleanup for cpu_clock_perf_event_update() Xiao Guangrong
2009-12-09 8:54 ` Frederic Weisbecker [this message]
2009-12-09 9:52 ` [tip:perf/urgent] perf_event: Cleanup " tip-bot for Xiao Guangrong
2009-12-09 8:43 ` [PATCH 2/3] perf_event: allocate children's perf_event_ctxp at the right time Frederic Weisbecker
2009-12-09 9:52 ` [tip:perf/urgent] perf_event: Allocate " tip-bot for Xiao Guangrong
2009-12-09 8:33 ` [PATCH 1/3] perf_event: cleanup for __perf_event_init_context() Frederic Weisbecker
2009-12-09 9:52 ` [tip:perf/urgent] perf_event: Clean up __perf_event_init_context() tip-bot for Xiao Guangrong
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