Commit-ID: 1e02cd40f15190b78fcc6b3f50c952fb4028e9a5 Gitweb: http://git.kernel.org/tip/1e02cd40f15190b78fcc6b3f50c952fb4028e9a5 Author: Peter Zijlstra <[email protected]> AuthorDate: Thu, 10 Mar 2016 15:39:24 +0100 Committer: Ingo Molnar <[email protected]> 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) <[email protected]> Reviewed-by: Alexander Shishkin <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: David Ahern <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Stephane Eranian <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Vince Weaver <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- 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); }
