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SubjectRe: [RFC PATCH v6 5/5] perf sched: prefer to use prev_state_char introduced in sched_switch
On Thu, Aug 3, 2023 at 5:34 PM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Thu, 3 Aug 2023 04:33:52 -0400
> Ze Gao <zegao2021@gmail.com> wrote:
>
> > Since the sched_switch tracepoint introduces a new variable to
> > report sched-out task state in symbolic char, we prefer to use
> > it to spare from knowing internal implementations in kernel.
>
> The above needs to be rewritten to be more comprehensive.
> Feel free to reply to this thread with new versions of the change log and
> such. No need to send a new patch series to fix this before you know that
> the new version is acceptable or not.

Copy that! Thank you.

> Replying to a current patch series is fine, but sending out a new one
> causes the spam as it's much easier to ignore a thread than to ignore a new
> thread with a new series.

Thanks Steven! Lesson learned.

Regards,
Ze

>
>
> >
> > Also we keep the old parsing logic intact but sync the state char
> > array with the latest kernel.
> >
> > Signed-off-by: Ze Gao <zegao@tencent.com>
> > ---
> > tools/perf/builtin-sched.c | 19 +++++++++++++++----
> > 1 file changed, 15 insertions(+), 4 deletions(-)
> >
> > diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
> > index 5042874ba204..6f99a36206c9 100644
> > --- a/tools/perf/builtin-sched.c
> > +++ b/tools/perf/builtin-sched.c
> > @@ -837,7 +837,7 @@ replay_wakeup_event(struct perf_sched *sched,
> >
> > static inline char task_state_char(int state)
> > {
> > - static const char state_to_char[] = "RSDTtXZPI";
> > + static const char state_to_char[] = "RSDTtXZPIp";
> > unsigned int bit = state ? ffs(state) : 0;
> >
> > return bit < sizeof(state_to_char) - 1 ? state_to_char[bit] : '?';
> > @@ -846,9 +846,20 @@ static inline char task_state_char(int state)
> > static inline char get_task_prev_state(struct evsel *evsel,
> > struct perf_sample *sample)
> > {
> > - const int prev_state = evsel__intval(evsel, sample, "prev_state");
> > + char prev_state_char;
> > + int prev_state;
> >
> > - return task_state_char(prev_state);
> > + /* prefer to use prev_state_char */
> > + if (evsel__field(evsel, "prev_state_char"))
> > + prev_state_char = (char) evsel__intval(evsel,
> > + sample, "prev_state_char");
> > + else {
> > + prev_state = (int) evsel__intval(evsel,
> > + sample, "prev_state");
> > + prev_state_char = task_state_char(prev_state);
> > + }
> > +
> > + return prev_state_char;
> > }
> >
> > static int replay_switch_event(struct perf_sched *sched,
> > @@ -2145,7 +2156,7 @@ static void timehist_update_runtime_stats(struct thread_runtime *r,
> > else if (r->last_time) {
> > u64 dt_wait = tprev - r->last_time;
> >
> > - if (r->last_state == 'R')
> > + if (r->last_state == 'R' || r->last_state == 'p')
> > r->dt_preempt = dt_wait;
> > else if (r->last_state == 'D')
> > r->dt_iowait = dt_wait;
>

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