perf sched: Show start of latency as well
The 'perf sched latency' tool is really useful at showing worst-case
latencies that task encountered since wakeup. However it shows only the
end of the latency. Often times the start of a latency is interesting as
it can show what else was going on at the time to cause the latency. I
certainly myself spending a lot of time backtracking to the start of the
latency in "perf sched script" which wastes a lot of time.
This patch therefore adds a new column "Max delay start". Considering
this, also rename "Maximum delay at" to "Max delay end" as its easier to
understand.
Example of the new output:
----------------------------------------------------------------------------------------------------------------------------------
Task | Runtime ms | Switches | Avg delay ms | Max delay ms | Max delay start | Max delay end |
----------------------------------------------------------------------------------------------------------------------------------
MediaScannerSer:11936 | 651.296 ms | 67978 | avg: 0.113 ms | max: 77.250 ms | max start: 477.691360 s | max end: 477.768610 s
audio@2.0-servi:(3) | 0.000 ms | 3440 | avg: 0.034 ms | max: 72.267 ms | max start: 477.697051 s | max end: 477.769318 s
AudioOut_1D:8112 | 0.000 ms | 2588 | avg: 0.083 ms | max: 64.020 ms | max start: 477.710740 s | max end: 477.774760 s
Time-limited te:14973 | 7966.090 ms | 24807 | avg: 0.073 ms | max: 15.563 ms | max start: 477.162746 s | max end: 477.178309 s
surfaceflinger:8049 | 9.680 ms | 603 | avg: 0.063 ms | max: 13.275 ms | max start: 476.931791 s | max end: 476.945067 s
HeapTaskDaemon:(3) | 1588.830 ms | 7040 | avg: 0.065 ms | max: 6.880 ms | max start: 473.666043 s | max end: 473.672922 s
mount-passthrou:(3) | 1370.809 ms | 68904 | avg: 0.011 ms | max: 6.524 ms | max start: 478.090630 s | max end: 478.097154 s
ReferenceQueueD:(3) | 11.794 ms | 1725 | avg: 0.014 ms | max: 6.521 ms | max start: 476.119782 s | max end: 476.126303 s
writer:14077 | 18.410 ms | 1427 | avg: 0.036 ms | max: 6.131 ms | max start: 474.169675 s | max end: 474.175805 s
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20200925235634.4089867-1-joel@joelfernandes.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index e6fc297..0e16f9d 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -130,7 +130,8 @@ struct work_atoms {
struct thread *thread;
struct rb_node node;
u64 max_lat;
- u64 max_lat_at;
+ u64 max_lat_start;
+ u64 max_lat_end;
u64 total_lat;
u64 nb_atoms;
u64 total_runtime;
@@ -1096,7 +1097,8 @@ add_sched_in_event(struct work_atoms *atoms, u64 timestamp)
atoms->total_lat += delta;
if (delta > atoms->max_lat) {
atoms->max_lat = delta;
- atoms->max_lat_at = timestamp;
+ atoms->max_lat_start = atom->wake_up_time;
+ atoms->max_lat_end = timestamp;
}
atoms->nb_atoms++;
}
@@ -1322,7 +1324,7 @@ static void output_lat_thread(struct perf_sched *sched, struct work_atoms *work_
int i;
int ret;
u64 avg;
- char max_lat_at[32];
+ char max_lat_start[32], max_lat_end[32];
if (!work_list->nb_atoms)
return;
@@ -1344,13 +1346,14 @@ static void output_lat_thread(struct perf_sched *sched, struct work_atoms *work_
printf(" ");
avg = work_list->total_lat / work_list->nb_atoms;
- timestamp__scnprintf_usec(work_list->max_lat_at, max_lat_at, sizeof(max_lat_at));
+ timestamp__scnprintf_usec(work_list->max_lat_start, max_lat_start, sizeof(max_lat_start));
+ timestamp__scnprintf_usec(work_list->max_lat_end, max_lat_end, sizeof(max_lat_end));
- printf("|%11.3f ms |%9" PRIu64 " | avg:%9.3f ms | max:%9.3f ms | max at: %13s s\n",
+ printf("|%11.3f ms |%9" PRIu64 " | avg:%8.3f ms | max:%8.3f ms | max start: %12s s | max end: %12s s\n",
(double)work_list->total_runtime / NSEC_PER_MSEC,
work_list->nb_atoms, (double)avg / NSEC_PER_MSEC,
(double)work_list->max_lat / NSEC_PER_MSEC,
- max_lat_at);
+ max_lat_start, max_lat_end);
}
static int pid_cmp(struct work_atoms *l, struct work_atoms *r)
@@ -3137,7 +3140,8 @@ static void __merge_work_atoms(struct rb_root_cached *root, struct work_atoms *d
list_splice(&data->work_list, &this->work_list);
if (this->max_lat < data->max_lat) {
this->max_lat = data->max_lat;
- this->max_lat_at = data->max_lat_at;
+ this->max_lat_start = data->max_lat_start;
+ this->max_lat_end = data->max_lat_end;
}
zfree(&data);
return;
@@ -3176,9 +3180,9 @@ static int perf_sched__lat(struct perf_sched *sched)
perf_sched__merge_lat(sched);
perf_sched__sort_lat(sched);
- printf("\n -----------------------------------------------------------------------------------------------------------------\n");
- printf(" Task | Runtime ms | Switches | Average delay ms | Maximum delay ms | Maximum delay at |\n");
- printf(" -----------------------------------------------------------------------------------------------------------------\n");
+ printf("\n -------------------------------------------------------------------------------------------------------------------------------------------\n");
+ printf(" Task | Runtime ms | Switches | Avg delay ms | Max delay ms | Max delay start | Max delay end |\n");
+ printf(" -------------------------------------------------------------------------------------------------------------------------------------------\n");
next = rb_first_cached(&sched->sorted_atom_root);