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author | Ian Rogers <irogers@google.com> | 2021-12-23 10:56:22 -0800 |
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committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2022-02-15 17:15:33 -0300 |
commit | 87a73bdc421ac702c248002a0a2e62f08c6e7682 (patch) | |
tree | 017df856afa33bc346462b180a243c15f0cbf9b6 /tools/perf/builtin-annotate.c | |
parent | aca8af3c2e8cb57662e6035c0ccb3c111a11d97a (diff) | |
download | linux-87a73bdc421ac702c248002a0a2e62f08c6e7682.tar.gz linux-87a73bdc421ac702c248002a0a2e62f08c6e7682.tar.bz2 linux-87a73bdc421ac702c248002a0a2e62f08c6e7682.zip |
perf test: Make metric testing more robust
When testing metric expressions we fake counter values from 1 going
upward. For some metrics this can yield negative values that are clipped
to zero, and then cause divide by zero failures.
Such clipping is questionable but may be a result of tools automatically
generating metrics. A workaround for this case is to try a second time
with counter values going in the opposite direction.
This case was seen in a metric like:
event1 / max(event2 - event3, 0)
But it may also happen in more sensible metrics like:
event1 / (event2 + event3 - 1 - event4)
Reviewed-by: John Garry <john.garry@huawei.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20211223185622.3435128-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/builtin-annotate.c')
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