linux-kernel - Re: [PATCH 1/2] perf sched: Introduce timehist command

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Message-ID: <871u1vptty.fsf@sejong.aot.lge.com>
Date:	Mon, 02 Dec 2013 16:58:49 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	David Ahern <dsahern@...il.com>
Cc:	acme@...stprotocols.net, linux-kernel@...r.kernel.org,
	Ingo Molnar <mingo@...nel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Mike Galbraith <efault@....de>, Jiri Olsa <jolsa@...hat.com>,
	Stephane Eranian <eranian@...gle.com>,
	Pekka Enberg <penberg@...nel.org>
Subject: Re: [PATCH 1/2] perf sched: Introduce timehist command - v2

On Sun,  1 Dec 2013 17:23:14 -0700, David Ahern wrote:
> 'perf sched timehist' provides an analysis of scheduling events.
>
> Example usage:
>     perf sched record -- sleep 1
>     perf sched timehist
>
> By default it shows the individual schedule events, including the time between
> sched-in events for the task, the task scheduling delay (time between wakeup
> and actually running) and run time for the task:
>
>            time cpu  task name[tid/pid]    b/n time sch delay  run time
>   ------------- ---- -------------------- --------- --------- ---------
>    79371.874569 [11] gcc[31949]               0.014     0.000     1.148
>    79371.874591 [10] gcc[31951]               0.000     0.000     0.024
>    79371.874603 [10] migration/10[59]         3.350     0.004     0.011
>    79371.874604 [11] <idle>                   1.148     0.000     0.035
>    79371.874723 [05] <idle>                   0.016     0.000     1.383
>    79371.874746 [05] gcc[31949]               0.153     0.078     0.022
> ...
>
> Times are in msec.usec.

Hmm.. I'm not sure this is right.  It probably confuse users since
timehist_time_str() still uses "sec.usec" format and it looks not
natural for me to use "msec".

Yeah, I see perf stat uses "msec.usec" for result of clock events but
AFAICT it also shows the unit explicitly.  And perf stat -I uses
"sec.nsec" format and perf script also uses "sec.usec" format so there's
a little consistency here.

I think this "msec.usec" format fits well for the scheduling events but
in general "sec.usec" format looks better IMHO.

Thanks,
Namhyung
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