diff options
| author | Ravi Bangoria <ravi.bangoria@amd.com> | 2022-06-04 10:15:12 +0530 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2022-06-24 13:18:22 -0300 |
| commit | 9ab95b0b15a092abb7c3309f3580f572a041f9ab (patch) | |
| tree | 50d9edc8b3d0e7e65405eabb552b7ed09d726afb /tools/perf/util/evsel.c | |
| parent | 52f28b7bac75da9b8508f17438c9a8d83ab48e5d (diff) | |
perf record ibs: Warn about sampling period skew
Samples without an L3 miss are discarded and counter is reset with
random value (between 1-15 for fetch PMU and 1-127 for op PMU) when IBS
L3 miss filtering is enabled. This causes a sampling period skew but
there is no way to reconstruct aggregated sampling period. So print a
warning at perf record if user sets l3missonly=1.
Ex:
# perf record -c 10000 -C 0 -e ibs_op/l3missonly=1/
WARNING: Hw internally resets sampling period when L3 Miss Filtering is enabled
and tagged operation does not cause L3 Miss. This causes sampling period skew.
Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com>
Acked-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ananth Narayan <ananth.narayan@amd.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kim Phillips <kim.phillips@amd.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Richter <rrichter@amd.com>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Santosh Shukla <santosh.shukla@amd.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: like.xu.linux@gmail.com
Cc: x86@kernel.org
Link: http://lore.kernel.org/lkml/20220604044519.594-2-ravi.bangoria@amd.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/evsel.c')
| -rw-r--r-- | tools/perf/util/evsel.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index ce499c5da8d7..8fea51a9cd90 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -1091,6 +1091,11 @@ void __weak arch_evsel__fixup_new_cycles(struct perf_event_attr *attr __maybe_un { } +void __weak arch__post_evsel_config(struct evsel *evsel __maybe_unused, + struct perf_event_attr *attr __maybe_unused) +{ +} + static void evsel__set_default_freq_period(struct record_opts *opts, struct perf_event_attr *attr) { @@ -1366,6 +1371,8 @@ void evsel__config(struct evsel *evsel, struct record_opts *opts, */ if (evsel__is_dummy_event(evsel)) evsel__reset_sample_bit(evsel, BRANCH_STACK); + + arch__post_evsel_config(evsel, attr); } int evsel__set_filter(struct evsel *evsel, const char *filter) |