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.
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