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authorJiri Olsa <jolsa@kernel.org>2017-07-14 18:35:51 +0200
committerIngo Molnar <mingo@kernel.org>2017-07-18 14:13:41 +0200
commitdc853e26f73e903e0c87e24f2695b5dcf33b3bc1 (patch)
tree0b6539cacfa3cd42d24d35851674988226359c94 /kernel
parentdd0b06b551f6b14da19582e301814746d838965a (diff)
perf/x86/intel: Fix debug_store reset field for freq events
There's a bug in PEBs event enabling code, that prevents PEBS freq events to work properly after non freq PEBS event was run. freq events - perf_event_attr::freq set -F <freq> option of perf record PEBS events - perf_event_attr::precise_ip > 0 default for perf record Like in following example with CPU 0 busy, we expect ~10000 samples for following perf tool run: # perf record -F 10000 -C 0 sleep 1 [ perf record: Woken up 2 times to write data ] [ perf record: Captured and wrote 0.640 MB perf.data (10031 samples) ] Everything's fine, but once we run non freq PEBS event like: # perf record -c 10000 -C 0 sleep 1 [ perf record: Woken up 4 times to write data ] [ perf record: Captured and wrote 1.053 MB perf.data (20061 samples) ] the freq events start to fail like this: # perf record -F 10000 -C 0 sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.185 MB perf.data (40 samples) ] The issue is in non freq PEBs event initialization of debug_store reset field, which value is used to auto-reload the counter value after PEBS event drain. This value is not being used for PEBS freq events, but once we run non freq event it stays in debug_store data and screws the sample_freq counting for PEBS freq events. Setting the reset field to 0 for freq events. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Kan Liang <kan.liang@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20170714163551.19459-1-jolsa@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
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