[PATCH 1/2] perf sched timehist: Fix --idle-hist when no callchains

Namhyung Kim
2016-12-13T08:07:49Z

When idle hist is enabled, the itr->last_thread should be set so that
it can find which thread run before idle task. But it was only set in
the save_idle_callchain(). This makes idle task doesn't show up in
the output when callchain is not recorded.

Before:

$ perf sched timehist --idle-hist
Samples do not have callchains.
time cpu task name wait time sch delay run time
[tid/pid] (msec) (msec) (msec)
--------------- ------ -------------------- --------- --------- ---------
197731.753834 [0001] perf[27469] 0.000 0.000 0.000
197731.753915 [0003] migration/3[23] 0.000 0.000 0.000
197731.754335 [0002] firefox[17773/17739] 0.000 0.000 0.000
197731.754486 [0001] sleep[27470] 0.000 0.000 0.000
197731.754981 [0002] firefox[17773/17739] 0.000 0.000 0.000
197731.755994 [0002] firefox[17773/17739] 0.000 0.000 0.000
...

After:

197731.753834 [0001] perf[27469] 0.000 0.000 0.000
197731.753914 [0001] <idle> 0.000 0.000 0.079
197731.753915 [0003] migration/3[23] 0.000 0.000 0.000
197731.754335 [0002] firefox[17773/17739] 0.000 0.000 0.000
197731.754486 [0001] sleep[27470] 0.000 0.000 0.000
197731.754903 [0002] <idle> 0.047 0.000 0.567
197731.754981 [0002] firefox[17773/17739] 0.000 0.000 0.567
197731.755922 [0002] <idle> 0.078 0.000 0.941
197731.755994 [0002] firefox[17773/17739] 0.000 0.000 0.941
197731.756625 [0003] <idle> 0.123 0.000 2.709
...

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
tools/perf/builtin-sched.c | 33 +++++++++++++++++----------------
1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 0750e938a656..405a91d0515f 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -2102,26 +2102,12 @@ static struct thread *get_idle_thread(int cpu)
return idle_threads[cpu];
}

-static void save_idle_callchain(struct thread *thread,
+static void save_idle_callchain(struct idle_thread_runtime *itr,
struct perf_sample *sample)
{
- struct thread *idle;
- struct idle_thread_runtime *itr;
-
if (!symbol_conf.use_callchain || sample->callchain == NULL)
return;

- idle = get_idle_thread(sample->cpu);
- if (idle == NULL) {
- pr_err("Failed to get idle thread for cpu %d.\n", sample->cpu);
- return;
- }
-
- itr = thread__priv(idle);
- if (itr == NULL)
- return;
-
- itr->last_thread = thread;
callchain_cursor__copy(&itr->cursor, &callchain_cursor);
}

@@ -2179,9 +2165,24 @@ static struct thread *timehist_get_thread(struct perf_sched *sched,

save_task_callchain(sched, sample, evsel, machine);
if (sched->idle_hist) {
+ struct thread *idle;
+ struct idle_thread_runtime *itr;
+
+ idle = get_idle_thread(sample->cpu);
+ if (idle == NULL) {
+ pr_err("Failed to get idle thread for cpu %d.\n", sample->cpu);
+ return NULL;
+ }
+
+ itr = thread__priv(idle);
+ if (itr == NULL)
+ return NULL;
+
+ itr->last_thread = thread;
+
/* copy task callchain when entering to idle */
if (perf_evsel__intval(evsel, sample, "next_pid") == 0)
- save_idle_callchain(thread, sample);
+ save_idle_callchain(itr, sample);
}
}

--
2.10.2