linux-kernel - Re: [PATCH 2/2] perf sched timehist: Fix invalid runtime in the idle hist

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Date:   Tue, 13 Dec 2016 19:54:42 +0900
From:   Namhyung Kim <namhyung@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Jiri Olsa <jolsa@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        David Ahern <dsahern@...il.com>,
        Andi Kleen <andi@...stfloor.org>,
        Minchan Kim <minchan@...nel.org>
Subject: Re: [PATCH 2/2] perf sched timehist: Fix invalid runtime in the idle
 hist

On Tue, Dec 13, 2016 at 07:32:36AM -0300, Arnaldo Carvalho de Melo wrote:
> Em Tue, Dec 13, 2016 at 05:06:32PM +0900, Namhyung Kim escreveu:
> > When --idle-hist option is used, run/wait time and sched delay value
> > should be shown for idle task only.  But due to internal accounting, a
> > last thread has same value of next idle task's and it was shown.
> > 
> > In the below example, firefox after idle task has same run time of
> > idle task's.
> 
> Same as last message, is this something I can fold into a patch yet in
> my perf/core branch?

Yep,

Fixes: 78de3657008b ("perf sched timehist: Add -I/--idle-hist option")

I guess it makes a conflict on the callchain code.  In case it doesn't
look obvious to resolve, please let me know..

Thanks,
Namhyung


> 
> - Arnaldo
>  
> >   $ 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)
> >   --------------- ------  --------------------  ---------  ---------  ---------
> >     197731.754335 [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
> >   <SNIP>
> > 
> > Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> > ---
> >  tools/perf/builtin-sched.c | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> > 
> > diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
> > index 405a91d0515f..64a0959bccd7 100644
> > --- a/tools/perf/builtin-sched.c
> > +++ b/tools/perf/builtin-sched.c
> > @@ -2439,6 +2439,15 @@ static int timehist_sched_change_event(struct perf_tool *tool,
> >  				goto out;
> >  
> >  			timehist_update_runtime_stats(last_tr, t, tprev);
> > +			/*
> > +			 * remove delta time of last thread as it's not updated
> > +			 * and otherwise it will show an invalid value next
> > +			 * time.  we only care total run time and run stat.
> > +			 */
> > +			last_tr->dt_run = 0;
> > +			last_tr->dt_wait = 0;
> > +			last_tr->dt_delay = 0;
> > +
> >  			if (itr->cursor.nr)
> >  				callchain_append(&itr->callchain, &itr->cursor,
> >  						 t - tprev);
> > -- 
> > 2.10.2