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Stephane Eranian authored
commit 61b87cae upstream. This patch fixes a bug in the filter_events() function. The patch fixes the bug whereby if some mappings did not exist, e.g., STALLED_CYCLES_FRONTEND, then any event after it in the attrs array would disappear from the published list of events in /sys/devices/cpu/events. This could be verified easily on any system post SNB (which do not publish STALLED_CYCLES_FRONTEND): $ ./perf stat -e cycles,ref-cycles true Performance counter stats for 'true': 1,217,348 cycles <not supported> ref-cycles The problem is that in filter_events() there is an assumption that the argument (attrs) is organized in increasing continuous event indexes related to the event_map(). But if we remove the non-supported events by shifing the position in the array, then the lookup x86_pmu.event_map() needs to compensate for it, otherwise we are looking up the wrong index. This patch corrects this problem by compensating for the deleted events and with that ref-cycles reappears (here shown on Haswell): $ perf stat -e ref-cycles,cycles true Performance counter stats for 'true': 4,525,910 ref-cycles 1,064,920 cycles 0.002943888 seconds time elapsed Signed-off-by:
Stephane Eranian <eranian@google.com> Signed-off-by:
Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: jolsa@kernel.org Cc: kan.liang@intel.com Fixes: 8300daa2 ("perf/x86: Filter out undefined events from sysfs events attribute") Link: http://lkml.kernel.org/r/1449516805-6637-1-git-send-email-eranian@google.comSigned-off-by:
Ingo Molnar <mingo@kernel.org> Signed-off-by:
Luis Henriques <luis.henriques@canonical.com>
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