linux-kernel - Re: [PATCH] alpha: convert perf_event to use local

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Date:	Thu, 12 Aug 2010 09:50:33 -0400
From:	Matt Turner <mattst88@...il.com>
To:	Michael Cree <mcree@...on.net.nz>
Cc:	linux-kernel@...r.kernel.org, Richard Henderson <rth@...ddle.net>,
	Ivan Kokshaysky <ink@...assic.park.msu.ru>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-alpha@...r.kernel.org
Subject: Re: [PATCH] alpha: convert perf_event to use local_t

On Thu, Aug 12, 2010 at 5:49 AM, Michael Cree <mcree@...on.net.nz> wrote:
> Updates the Alpha perf_event code to match the changes
> recently made to the core perf_event code in commit
> e78505958cf123048fb48cb56b79cebb8edd15fb.
>
> Signed-off-by: Michael Cree <mcree@...on.net.nz>
> ---
>  arch/alpha/kernel/perf_event.c |   18 +++++++++---------
>  1 files changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/arch/alpha/kernel/perf_event.c b/arch/alpha/kernel/perf_event.c
> index 51c39fa..85d8e4f 100644
> --- a/arch/alpha/kernel/perf_event.c
> +++ b/arch/alpha/kernel/perf_event.c
> @@ -241,20 +241,20 @@ static inline unsigned long alpha_read_pmc(int idx)
>  static int alpha_perf_event_set_period(struct perf_event *event,
>                                struct hw_perf_event *hwc, int idx)
>  {
> -       long left = atomic64_read(&hwc->period_left);
> +       long left = local64_read(&hwc->period_left);
>        long period = hwc->sample_period;
>        int ret = 0;
>
>        if (unlikely(left <= -period)) {
>                left = period;
> -               atomic64_set(&hwc->period_left, left);
> +               local64_set(&hwc->period_left, left);
>                hwc->last_period = period;
>                ret = 1;
>        }
>
>        if (unlikely(left <= 0)) {
>                left += period;
> -               atomic64_set(&hwc->period_left, left);
> +               local64_set(&hwc->period_left, left);
>                hwc->last_period = period;
>                ret = 1;
>        }
> @@ -269,7 +269,7 @@ static int alpha_perf_event_set_period(struct perf_event *event,
>        if (left > (long)alpha_pmu->pmc_max_period[idx])
>                left = alpha_pmu->pmc_max_period[idx];
>
> -       atomic64_set(&hwc->prev_count, (unsigned long)(-left));
> +       local64_set(&hwc->prev_count, (unsigned long)(-left));
>
>        alpha_write_pmc(idx, (unsigned long)(-left));
>
> @@ -300,10 +300,10 @@ static unsigned long alpha_perf_event_update(struct perf_event *event,
>        long delta;
>
>  again:
> -       prev_raw_count = atomic64_read(&hwc->prev_count);
> +       prev_raw_count = local64_read(&hwc->prev_count);
>        new_raw_count = alpha_read_pmc(idx);
>
> -       if (atomic64_cmpxchg(&hwc->prev_count, prev_raw_count,
> +       if (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
>                             new_raw_count) != prev_raw_count)
>                goto again;
>
> @@ -316,8 +316,8 @@ again:
>                delta += alpha_pmu->pmc_max_period[idx] + 1;
>        }
>
> -       atomic64_add(delta, &event->count);
> -       atomic64_sub(delta, &hwc->period_left);
> +       local64_add(delta, &event->count);
> +       local64_sub(delta, &hwc->period_left);
>
>        return new_raw_count;
>  }
> @@ -636,7 +636,7 @@ static int __hw_perf_event_init(struct perf_event *event)
>        if (!hwc->sample_period) {
>                hwc->sample_period = alpha_pmu->pmc_max_period[0];
>                hwc->last_period = hwc->sample_period;
> -               atomic64_set(&hwc->period_left, hwc->sample_period);
> +               local64_set(&hwc->period_left, hwc->sample_period);
>        }
>
>        return 0;
> --
> 1.7.1
>
>

Thanks Michael. I'll apply this when I get back from vacation.
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