Peter Zijlstra <pet...@infradead.org> writes:
> On Wed, Dec 11, 2013 at 02:36:13PM +0200, Alexander Shishkin wrote:
>> Currently, only one pmu in a context gets disabled during unthrottling
>> and event_sched_{out,in}, however, events in one context may belong to
>> different pmus, which results in pmus being reprogrammed while they are
>> still enabled. This patch temporarily disables pmus that correspond to
>> each event in the context while these events are being modified.
>>
>> Signed-off-by: Alexander Shishkin <alexander.shish...@linux.intel.com>
>> ---
>> kernel/events/core.c | 27 ++++++++++++++++++++++++---
>> 1 file changed, 24 insertions(+), 3 deletions(-)
>>
>> diff --git a/kernel/events/core.c b/kernel/events/core.c
>> index 403b781..d656cd6 100644
>> --- a/kernel/events/core.c
>> +++ b/kernel/events/core.c
>> @@ -1396,6 +1396,9 @@ event_sched_out(struct perf_event *event,
>> if (event->state != PERF_EVENT_STATE_ACTIVE)
>> return;
>>
>> + if (event->pmu != ctx->pmu)
>> + perf_pmu_disable(event->pmu);
>> +
>> event->state = PERF_EVENT_STATE_INACTIVE;
>> if (event->pending_disable) {
>> event->pending_disable = 0;
>> @@ -1412,6 +1415,9 @@ event_sched_out(struct perf_event *event,
>> ctx->nr_freq--;
>> if (event->attr.exclusive || !cpuctx->active_oncpu)
>> cpuctx->exclusive = 0;
>> +
>> + if (event->pmu != ctx->pmu)
>> + perf_pmu_enable(event->pmu);
>> }
>>
>> static void
>
> Hmm, indeed. Does it make sense to drop the conditional?
> perf_pmu_{en,dis}able() is recursive and the thinking is that if its the
> same PMU the cacheline is hot because we touched it already recently
> anyway, so the unconditional inc/dec might actually be faster.. dunno.
Well, given the disable_count check in perf_pmu_{en,dis}able, this one
indeed looks redundant to me. Should I resend this one separately?
Regards,
--
Alex
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