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| -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] |