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perf sched timehist: Fixed timestamp error when unable to confirm event sched_in time

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[ Upstream commit 39c243411bdb8fb35777adf49ee32549633c4e12 ]

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: 853b740711 ("perf sched timehist: Add option to specify time window of interest")
Signed-off-by: Yang Jihong <[email protected]>
Acked-by: Namhyung Kim <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: James Clark <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
This commit is contained in:
Yang Jihong 2024-08-19 10:47:20 +08:00 • committed by Greg Kroah-Hartman
commit fc8d057930
1 changed files with 4 additions and 1 deletions
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5
tools/perf/builtin-sched.c
View file

@ -2561,9 +2561,12 @@ static int timehist_sched_change_event(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)