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SubjectRe: [PATCH 1/2] perf sched timehist: Fix -g/--call-graph option failure
On Wed, Mar 27, 2024 at 10:59 PM Yang Jihong <yangjihong@bytedance.com> wrote:
>
> When perf-sched enables the call-graph recording, sample_type of dummy
> event does not have PERF_SAMPLE_CALLCHAIN, timehist_check_attr() checks
> that the evsel does not have a callchain, and set show_callchain to 0.
>
> Currently perf sched timehist only saves callchain when processing
> sched:sched_switch event, timehist_check_attr() only needs to determine
> whether the event has PERF_SAMPLE_CALLCHAIN.
>
> Before:
> # perf sched record -g true
> [ perf record: Woken up 0 times to write data ]
> [ perf record: Captured and wrote 4.153 MB perf.data (7536 samples) ]
> # perf sched timehist
> Samples do not have callchains.
> time cpu task name wait time sch delay run time
> [tid/pid] (msec) (msec) (msec)
> --------------- ------ ------------------------------ --------- --------- ---------
> 147851.826019 [0000] perf[285035] 0.000 0.000 0.000
> 147851.826029 [0000] migration/0[15] 0.000 0.003 0.009
> 147851.826063 [0001] perf[285035] 0.000 0.000 0.000
> 147851.826069 [0001] migration/1[21] 0.000 0.003 0.006
> <SNIP>
>
> After:
> # perf sched record -g true
> [ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 2.572 MB perf.data (822 samples) ]
> # perf sched timehist
> time cpu task name wait time sch delay run time
> [tid/pid] (msec) (msec) (msec)
> --------------- ------ ------------------------------ --------- --------- ---------
> 144193.035164 [0000] perf[277062] 0.000 0.000 0.000 __traceiter_sched_switch <- __traceiter_sched_switch <- __sched_text_start <- preempt_schedule_common <- __cond_resched <- __wait_for_common <- wait_for_completion
> 144193.035174 [0000] migration/0[15] 0.000 0.003 0.009 __traceiter_sched_switch <- __traceiter_sched_switch <- __sched_text_start <- smpboot_thread_fn <- kthread <- ret_from_fork
> 144193.035207 [0001] perf[277062] 0.000 0.000 0.000 __traceiter_sched_switch <- __traceiter_sched_switch <- __sched_text_start <- preempt_schedule_common <- __cond_resched <- __wait_for_common <- wait_for_completion
> 144193.035214 [0001] migration/1[21] 0.000 0.003 0.007 __traceiter_sched_switch <- __traceiter_sched_switch <- __sched_text_start <- smpboot_thread_fn <- kthread <- ret_from_fork
> <SNIP>

This looks good, should there be a Fixes tag for the sake of backports?

Thanks,
Ian

> Signed-off-by: Yang Jihong <yangjihong@bytedance.com>
> ---
> tools/perf/builtin-sched.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
> index b248c433529a..1bfb22347371 100644
> --- a/tools/perf/builtin-sched.c
> +++ b/tools/perf/builtin-sched.c
> @@ -2963,8 +2963,11 @@ static int timehist_check_attr(struct perf_sched *sched,
> return -1;
> }
>
> - if (sched->show_callchain && !evsel__has_callchain(evsel)) {
> - pr_info("Samples do not have callchains.\n");
> + /* only need to save callchain related to sched_switch event */
> + if (sched->show_callchain &&
> + evsel__name_is(evsel, "sched:sched_switch") &&
> + !evsel__has_callchain(evsel)) {
> + pr_info("Samples of sched_switch event do not have callchains.\n");
> sched->show_callchain = 0;
> symbol_conf.use_callchain = 0;
> }
> --
> 2.25.1
>

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