From f53d168c025f27d64417a56bf129dbb39d2e1189 Mon Sep 17 00:00:00 2001 From: "sukadev@linux.vnet.ibm.com" Date: Thu, 24 Jan 2013 13:25:23 +0000 Subject: [PATCH] perf/Power: PERF_EVENT_IOC_ENABLE does not reenable event perf/Power: PERF_EVENT_IOC_ENABLE does not reenable event If we disable a perf event because we exceeded the specified ->event_limit, power_pmu_stop() sets the PERF_HES_STOPPED flag on the event. If the application then re-enables the event using PERF_EVENT_IOC_ENABLE ioctl, we don't ever clear this STOPPED flag. Consequently, the user space is never notified of the event. Following message has more background and test case. http://lists.eecs.utk.edu/pipermail/ptools-perfapi/2012-October/002528.html Used the following test cases to verify that this patch works on latest PAPI. $ papi.git/src/ctests/nonthread PAPI_TOT_CYC@5000000 $ papi.git/src/ctests/overflow_single_event Changelog[v2]: - [Paul Mackerras] Also clear PERF_HES_UPTODATE flag since we are restarting the event; cleanup comments and patch description. Signed-off-by: Sukadev Bhattiprolu Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/perf/core-book3s.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c index 89bd593..069f92b 100644 --- a/arch/powerpc/perf/core-book3s.c +++ b/arch/powerpc/perf/core-book3s.c @@ -880,8 +880,16 @@ static int power_pmu_add(struct perf_event *event, int ef_flags) cpuhw->events[n0] = event->hw.config; cpuhw->flags[n0] = event->hw.event_base; + /* + * This event may have been disabled/stopped in record_and_restart() + * because we exceeded the ->event_limit. If re-starting the event, + * clear the ->hw.state (STOPPED and UPTODATE flags), so the user + * notification is re-enabled. + */ if (!(ef_flags & PERF_EF_START)) event->hw.state = PERF_HES_STOPPED | PERF_HES_UPTODATE; + else + event->hw.state = 0; /* * If group events scheduling transaction was started, -- 2.7.4