Commit-ID: 1e02cd40f15190b78fcc6b3f50c952fb4028e9a5 Gitweb: http://git.kernel.org/tip/1e02cd40f15190b78fcc6b3f50c952fb4028e9a5 Author: Peter Zijlstra <pet...@infradead.org> AuthorDate: Thu, 10 Mar 2016 15:39:24 +0100 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Mon, 21 Mar 2016 09:08:14 +0100
perf/core: Fix the unthrottle logic Its possible to IOC_PERIOD while the event is throttled, this would re-start the event and the next tick would then try to unthrottle it, and find the event wasn't actually stopped anymore. This would tickle a WARN in the x86-pmu code which isn't expecting to start a !stopped event. Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Reviewed-by: Alexander Shishkin <alexander.shish...@linux.intel.com> Cc: Andy Lutomirski <l...@amacapital.net> Cc: Arnaldo Carvalho de Melo <a...@redhat.com> Cc: Borislav Petkov <b...@alien8.de> Cc: Brian Gerst <brge...@gmail.com> Cc: David Ahern <dsah...@gmail.com> Cc: Denys Vlasenko <dvlas...@redhat.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Jiri Olsa <jo...@redhat.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Namhyung Kim <namhy...@kernel.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Stephane Eranian <eran...@google.com> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Vince Weaver <vincent.wea...@maine.edu> Cc: dvyu...@google.com Cc: o...@redhat.com Cc: pan...@redhat.com Cc: sasha.le...@oracle.com Cc: vi...@deater.net Link: http://lkml.kernel.org/r/20160310143924.gr6...@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mi...@kernel.org> --- kernel/events/core.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/kernel/events/core.c b/kernel/events/core.c index 712570d..d394773 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4210,6 +4210,14 @@ static void __perf_event_period(struct perf_event *event, active = (event->state == PERF_EVENT_STATE_ACTIVE); if (active) { perf_pmu_disable(ctx->pmu); + /* + * We could be throttled; unthrottle now to avoid the tick + * trying to unthrottle while we already re-started the event. + */ + if (event->hw.interrupts == MAX_INTERRUPTS) { + event->hw.interrupts = 0; + perf_log_throttle(event, 1); + } event->pmu->stop(event, PERF_EF_UPDATE); }
