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    SubjectRe: [PATCH 4/5] perf: Introduce task, softirq and hardirq contexts exclusion
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    On Thu, 2010-06-10 at 05:49 +0200, Frederic Weisbecker wrote:
    > @@ -642,17 +643,31 @@ event_sched_in(struct perf_event *event,
    > if (event->state <= PERF_EVENT_STATE_OFF)
    > return 0;
    >
    > - event->state = PERF_EVENT_STATE_ACTIVE;
    > + if (event->attr.exclude_task)
    > + event->state = PERF_EVENT_STATE_PAUSED;
    > + else
    > + event->state = PERF_EVENT_STATE_ACTIVE;
    > +
    > event->oncpu = smp_processor_id();
    > +

    Aah, so that is why you added the PAUSE state knowledge to the arch
    code, you want to be able to call ->enable() on a PAUSEd event.

    That means you need to audit/touch all implementations anyway, isn't
    there a better interface we can use, like maybe extend ->enable() with a
    flags argument?

    > /*
    > * The new state must be visible before we turn it on in the hardware:
    > */
    > smp_wmb();
    >
    > - if (event->pmu->enable(event)) {
    > - event->state = PERF_EVENT_STATE_INACTIVE;
    > - event->oncpu = -1;
    > - return -EAGAIN;
    > + /*
    > + * If we exclude the tasks, we only need to schedule hardware
    > + * events that need to settle themselves, even in a pause mode.
    > + * Software events can simply be scheduled anytime.
    > + * If we want more granularity in all that, we can still provide
    > + * later a pmu->reserve callback.
    > + */
    > + if (!event->attr.exclude_task || !is_software_event(event)) {
    > + if (event->pmu->enable(event)) {
    > + event->state = PERF_EVENT_STATE_INACTIVE;
    > + event->oncpu = -1;
    > + return -EAGAIN;
    > + }
    > }
    >
    > event->tstamp_running += ctx->time - event->tstamp_stopped;

    Remove is_software_event(), not add more.


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