diff options
| author | Howard Chu <howardchu95@gmail.com> | 2025-05-28 12:11:47 -0700 |
|---|---|---|
| committer | Namhyung Kim <namhyung@kernel.org> | 2025-06-09 11:18:20 -0700 |
| commit | 77e11efedba606af21224ee5ed5305aebbd029da (patch) | |
| tree | 2ba9217926a89f9e5b5d3162071ab9db4c5f929c /tools/perf/util/scripting-engines/trace-event-python.c | |
| parent | d796c51ee52a10413435816ebdae8a0aa8df8f93 (diff) | |
perf test trace: Use --sort-events in BTF general tests
Without the '--sort-events' flag, perf trace doesn't receive and process
events based on their arrival time, thus PERF_RECORD_COMM event that
assigns the correct comm to a PID, may be delivered and processed after
regular samples, causing trace outputs not having a 'comm', e.g.
'mv', instead, having the default PID placeholder, e.g. ':14514'.
Hopefully this answers Namhyung's question in [1].
You can simply justify the statement with this diff: [2].
Now, simply run this command multiple times:
$ touch /tmp/file1 && sudo /tmp/perf trace -e renameat* -- mv /tmp/file1 /tmp/file2 && rm -f /tmp/file2
And you should see two types of results:
$ touch /tmp/file1 && sudo /tmp/perf trace -e renameat* -- mv /tmp/file1 /tmp/file2 && rm -f /tmp/file2
[debug] deliver
[debug] machine__process_comm_event
[OVERRIDE] old :1221169 new mv str mv
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
0.000 ( 0.013 ms): mv/1221169 renameat2(olddfd: CWD, oldname: "/tmp/file1", newdfd: CWD, newname: "/tmp/file2", flags: NOREPLACE) = 0
[debug] deliver
$ touch /tmp/file1 && sudo /tmp/perf trace -e renameat* -- mv /tmp/file1 /tmp/file2 && rm -f /tmp/file2
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
[debug] deliver
0.000 ( 0.014 ms): :1221398/1221398 renameat2(olddfd: CWD, oldname: "/tmp/file1", newdfd: CWD, newname: "/tmp/file2", flags: NOREPLACE) = 0
[debug] deliver
[debug] deliver
[debug] machine__process_comm_event
[OVERRIDE] old :1221398 new mv str mv
[debug] deliver
[debug] deliver
[debug] deliver
Anyway, use --sort-events in BTF general tests to avoid :PID, a comm is
preferred.
[1]: https://lore.kernel.org/linux-perf-users/Z_AeswETE5xLcPT8@google.com/
[2]: https://gist.githubusercontent.com/Sberm/6b72b2a1cf1c62244f1f996481769baf/raw/529667bd74a2e7e1953bbd4be545bf875da8a3e7/unsorted.patch
Signed-off-by: Howard Chu <howardchu95@gmail.com>
Tested-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20250528191148.89118-6-howardchu95@gmail.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Diffstat (limited to 'tools/perf/util/scripting-engines/trace-event-python.c')
0 files changed, 0 insertions, 0 deletions