Hi Peter, Do you have any thoughts on the below? It would be good to add your signed-off to the patch, since you wrote it originally.
Cheers, Will On Wed, Nov 27, 2013 at 01:54:38PM +0000, Will Deacon wrote: > From: Peter Zijlstra <[email protected]> > > Vince Weaver reports that, on all architectures apart from ARM, > PERF_EVENT_IOC_PERIOD doesn't actually update the period until the next > event fires. This is counter-intuitive behaviour and is better dealt > with in the core code. > > This patch ensures that the period is forcefully reset when dealing with > such a request in the core code. A subsequent patch removes the > equivalent hack from the ARM back-end. > > Cc: Vince Weaver <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Signed-off-by: Will Deacon <[email protected]> > --- > > Peter -- I didn't want this to get lost, so I picked it up, fixed a typo > and wrote a commit message. Could I add your SoB please? > > Cheers, > Will > > kernel/events/core.c | 16 +++++++++++++++- > 1 file changed, 15 insertions(+), 1 deletion(-) > > diff --git a/kernel/events/core.c b/kernel/events/core.c > index d724e7757cd1..1c626b923ddf 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -3527,7 +3527,7 @@ static void perf_event_for_each(struct perf_event > *event, > static int perf_event_period(struct perf_event *event, u64 __user *arg) > { > struct perf_event_context *ctx = event->ctx; > - int ret = 0; > + int ret = 0, active; > u64 value; > > if (!is_sampling_event(event)) > @@ -3551,6 +3551,20 @@ static int perf_event_period(struct perf_event *event, > u64 __user *arg) > event->attr.sample_period = value; > event->hw.sample_period = value; > } > + > + active = (event->state == PERF_EVENT_STATE_ACTIVE); > + if (active) { > + perf_pmu_disable(ctx->pmu); > + event->pmu->stop(event, PERF_EF_UPDATE); > + } > + > + local64_set(&event->hw.period_left, 0); > + > + if (active) { > + event->pmu->start(event, PERF_EF_RELOAD); > + perf_pmu_enable(ctx->pmu); > + } > + > unlock: > raw_spin_unlock_irq(&ctx->lock); > > -- > 1.8.2.2 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
