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| author | Yang Jihong <yangjihong@bytedance.com> | 2024-08-19 10:47:20 +0800 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2024-08-30 10:31:57 -0300 |
| commit | 39c243411bdb8fb35777adf49ee32549633c4e12 (patch) | |
| tree | bfd12bc6fd2fb35deea64723ab78f6c6b1018be7 | |
| parent | 74fd69a35cae1d53d9c95b700aae312d77b0d1cb (diff) | |
| download | lwn-39c243411bdb8fb35777adf49ee32549633c4e12.tar.gz lwn-39c243411bdb8fb35777adf49ee32549633c4e12.zip | |
perf sched timehist: Fixed timestamp error when unable to confirm event sched_in time
If sched_in event for current task is not recorded, sched_in timestamp
will be set to end_time of time window interest, causing an error in
timestamp show. In this case, we choose to ignore this event.
Test scenario:
perf[1229608] does not record the first sched_in event, run time and sch delay are both 0
# perf sched timehist
Samples of sched_switch event do not have callchains.
time cpu task name wait time sch delay run time
[tid/pid] (msec) (msec) (msec)
--------------- ------ ------------------------------ --------- --------- ---------
2090450.763231 [0000] perf[1229608] 0.000 0.000 0.000
2090450.763235 [0000] migration/0[15] 0.000 0.001 0.003
2090450.763263 [0001] perf[1229608] 0.000 0.000 0.000
2090450.763268 [0001] migration/1[21] 0.000 0.001 0.004
2090450.763302 [0002] perf[1229608] 0.000 0.000 0.000
2090450.763309 [0002] migration/2[27] 0.000 0.001 0.007
2090450.763338 [0003] perf[1229608] 0.000 0.000 0.000
2090450.763343 [0003] migration/3[33] 0.000 0.001 0.004
Before:
arbitrarily specify a time window of interest, timestamp will be set to an incorrect value
# perf sched timehist --time 100,200
Samples of sched_switch event do not have callchains.
time cpu task name wait time sch delay run time
[tid/pid] (msec) (msec) (msec)
--------------- ------ ------------------------------ --------- --------- ---------
200.000000 [0000] perf[1229608] 0.000 0.000 0.000
200.000000 [0001] perf[1229608] 0.000 0.000 0.000
200.000000 [0002] perf[1229608] 0.000 0.000 0.000
200.000000 [0003] perf[1229608] 0.000 0.000 0.000
200.000000 [0004] perf[1229608] 0.000 0.000 0.000
200.000000 [0005] perf[1229608] 0.000 0.000 0.000
200.000000 [0006] perf[1229608] 0.000 0.000 0.000
200.000000 [0007] perf[1229608] 0.000 0.000 0.000
After:
# perf sched timehist --time 100,200
Samples of sched_switch event do not have callchains.
time cpu task name wait time sch delay run time
[tid/pid] (msec) (msec) (msec)
--------------- ------ ------------------------------ --------- --------- ---------
Fixes: 853b74071110bed3 ("perf sched timehist: Add option to specify time window of interest")
Signed-off-by: Yang Jihong <yangjihong@bytedance.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsa@cumulusnetworks.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240819024720.2405244-1-yangjihong@bytedance.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
| -rw-r--r-- | tools/perf/builtin-sched.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c index 9c1276dc8ef6..1c386ebe4b98 100644 --- a/tools/perf/builtin-sched.c +++ b/tools/perf/builtin-sched.c @@ -2683,9 +2683,12 @@ static int timehist_sched_change_event(const struct perf_tool *tool, * - previous sched event is out of window - we are done * - sample time is beyond window user cares about - reset it * to close out stats for time window interest + * - If tprev is 0, that is, sched_in event for current task is + * not recorded, cannot determine whether sched_in event is + * within time window interest - ignore it */ if (ptime->end) { - if (tprev > ptime->end) + if (!tprev || tprev > ptime->end) goto out; if (t > ptime->end) |