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

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Message-ID: <20161213103236.GH5482@kernel.org>
Date:   Tue, 13 Dec 2016 07:32:36 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Namhyung Kim <namhyung@...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

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?

- 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