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Message-ID: <20091209085417.GC5152@nowhere> Date: Wed, 9 Dec 2009 09:54:19 +0100 From: Frederic Weisbecker <fweisbec@...il.com> To: Xiao Guangrong <xiaoguangrong@...fujitsu.com> Cc: Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>, Paul Mackerras <paulus@...ba.org>, LKML <linux-kernel@...r.kernel.org> Subject: Re: [PATCH 3/3] perf_event: cleanup for cpu_clock_perf_event_update() 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@...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@...il.com> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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