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| author |   Ravi Bangoria <ravi.bangoria@amd.com> | 2025-05-23 15:21:55 -0700 |
|---|---|---|
| committer |   Arnaldo Carvalho de Melo <acme@redhat.com> | 2025-05-28 14:41:10 -0300 |
| commit | 00a23c000e13d4c66f38eefd530dc377cc90ec14 (patch) | |
| tree | 7b73a7f8b758347b4c0beaa13e7e9bd7f1937297 /tools/perf | |
| parent | perf record: Fix incorrect --user-regs comments (diff) | |
| download | linux-rng-00a23c000e13d4c66f38eefd530dc377cc90ec14.tar.xz linux-rng-00a23c000e13d4c66f38eefd530dc377cc90ec14.zip | |
perf mem: Describe overhead calculation in brief
Unlike perf-report which uses sample period for overhead calculation,
perf-mem overhead is calculated using sample weight. Describe perf-mem
overhead calculation method in it's man page.
Reviewed-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20250523222157.1259998-1-namhyung@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf')
| -rw-r--r-- | tools/perf/Documentation/perf-mem.txt | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/tools/perf/Documentation/perf-mem.txt b/tools/perf/Documentation/perf-mem.txt index a9e3c71a2205..965e73d37772 100644 --- a/tools/perf/Documentation/perf-mem.txt +++ b/tools/perf/Documentation/perf-mem.txt @@ -137,6 +137,25 @@ REPORT OPTIONS In addition, for report all perf report options are valid, and for record all perf record options. +OVERHEAD CALCULATION +-------------------- +Unlike linkperf:perf-report[1], which calculates overhead from the actual +sample period, perf-mem overhead is calculated using sample weight. E.g. +there are two samples in perf.data file, both with the same sample period, +but one sample with weight 180 and the other with weight 20: + + $ perf script -F period,data_src,weight,ip,sym + 100000 629080842 |OP LOAD|LVL L3 hit|... 20 7e69b93ca524 strcmp + 100000 1a29081042 |OP LOAD|LVL RAM hit|... 180 ffffffff82429168 memcpy + + $ perf report -F overhead,symbol + 50% [.] strcmp + 50% [k] memcpy + + $ perf mem report -F overhead,symbol + 90% [k] memcpy + 10% [.] strcmp + SEE ALSO -------- linkperf:perf-record[1], linkperf:perf-report[1], linkperf:perf-arm-spe[1] |