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

Arnaldo Carvalho de Melo
2016-12-13T10:32:09Z

Em Tue, Dec 13, 2016 at 05:06:31PM +0900, Namhyung Kim escreveu:
> 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.

It is important to provide a Fixes: tag so that I can check if the
problem was introduced by some patch still not sent to Ingo, in which
case I could try and merge them, is this the case here?

- Arnaldo

> 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