linux-kernel - Re: [PATCH] perf_events: improve x86 event scheduling

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Message-ID: <20100117161859.GG5035@nowhere>
Date:	Sun, 17 Jan 2010 17:19:00 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel@...r.kernel.org, mingo@...e.hu, paulus@...ba.org,
	davem@...emloft.net, perfmon2-devel@...ts.sf.net
Subject: Re: [PATCH] perf_events: improve x86 event scheduling

On Sun, Jan 17, 2010 at 03:42:16PM +0100, Stephane Eranian wrote:
> Frederic,
> 
> 
> Here is what I have now in the x86 code.
> 
> As for your comment on disabling the x86 event, we don't
> need to do this because it is not actually activated yet when
> we return from hw_perf_group_sched_in(). Activation occurs
> really in hw_perf_enable().


Ah, indeed.


> 
> 
> static int x86_event_sched_in(struct perf_event *event,
>                           struct perf_cpu_context *cpuctx, int cpu)
> {
>         int ret = 0;
> 
>         event->state = PERF_EVENT_STATE_ACTIVE;
>         event->oncpu = cpu;
>         event->tstamp_running += event->ctx->time - event->tstamp_stopped;
> 
>         if (is_software_event(event))
>                 ret = event->pmu->enable(event);
> 
>         if (!ret && !is_software_event(event))
>                 cpuctx->active_oncpu++;
> 
>         if (!ret && event->attr.exclusive)
>                 cpuctx->exclusive = 1;
> 
>         return ret;
> }
> 
> static void x86_event_sched_out(struct perf_event *event,
>                             struct perf_cpu_context *cpuctx, int cpu)
> {
>         event->state = PERF_EVENT_STATE_INACTIVE;
>         event->oncpu = -1;
> 
>         event->tstamp_running -= event->ctx->time - event->tstamp_stopped;
> 
>         if (is_software_event(event))
>                 event->pmu->disable(event);
> 
>         if (!is_software_event(event))
>                 cpuctx->active_oncpu--;
> 
>         if (event->attr.exclusive || !cpuctx->active_oncpu)
>                 cpuctx->exclusive = 0;
> }



Yeah looks good.

Thanks.

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