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H A D | core-book3s.c | f53d168c Thu Jan 24 07:25:23 CST 2013 sukadev@linux.vnet.ibm.com <sukadev@linux.vnet.ibm.com> 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 <sukadev@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> f53d168c Thu Jan 24 07:25:23 CST 2013 sukadev@linux.vnet.ibm.com <sukadev@linux.vnet.ibm.com> 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 <sukadev@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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