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perf evlist: Fix error out while applying initial delay and LBR
'perf record' will error out if both --delay and LBR are applied. For example: # perf record -D 1000 -a -e cycles -j any -- sleep 2 Error: dummy:HG: PMU Hardware doesn't support sampling/overflow-interrupts. Try 'perf stat' # A dummy event is added implicitly for initial delay, which has the same configurations as real sampling events. The dummy event is a software event. If LBR is configured, perf must error out. The dummy event will only be used to track PERF_RECORD_MMAP while perf waits for the initial delay to enable the real events. The BRANCH_STACK bit can be safely cleared for the dummy event. After applying the patch: # perf record -D 1000 -a -e cycles -j any -- sleep 2 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 1.054 MB perf.data (828 samples) ] # Reported-by: Sunil K Pandey <sunil.k.pandey@intel.com> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1531145722-16404-1-git-send-email-kan.liang@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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1 changed files with 14 additions and 0 deletions
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@ -859,6 +859,12 @@ static void apply_config_terms(struct perf_evsel *evsel,
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}
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}
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static bool is_dummy_event(struct perf_evsel *evsel)
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{
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return (evsel->attr.type == PERF_TYPE_SOFTWARE) &&
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(evsel->attr.config == PERF_COUNT_SW_DUMMY);
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}
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/*
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* The enable_on_exec/disabled value strategy:
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*
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@ -1097,6 +1103,14 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts,
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else
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perf_evsel__reset_sample_bit(evsel, PERIOD);
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}
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/*
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* For initial_delay, a dummy event is added implicitly.
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* The software event will trigger -EOPNOTSUPP error out,
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* if BRANCH_STACK bit is set.
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*/
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if (opts->initial_delay && is_dummy_event(evsel))
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perf_evsel__reset_sample_bit(evsel, BRANCH_STACK);
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}
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static int perf_evsel__alloc_fd(struct perf_evsel *evsel, int ncpus, int nthreads)
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