linux-kernel - Re: [PATCHSET 0/7] perf sched: Introduce timehist command, again (v1)

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Date:   Wed, 16 Nov 2016 00:32:39 +0900
From:   Namhyung Kim <namhyung@...nel.org>
To:     David Ahern <dsahern@...il.com>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Jiri Olsa <jolsa@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Stephane Eranian <eranian@...gle.com>,
        Andi Kleen <andi@...stfloor.org>
Subject: Re: [PATCHSET 0/7] perf sched: Introduce timehist command, again (v1)

Hi David,

On Tue, Nov 15, 2016 at 08:14:24AM -0700, David Ahern wrote:
> On 11/15/16 12:34 AM, Ingo Molnar wrote:
> > 
> > * Namhyung Kim <namhyung@...nel.org> wrote:
> > 
> >>>> 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
> >>>> ...
> >>>
> >>> What does the 'b/n' abbreviation stand for? 'Between'? Could we call the column 
> >>> 'sch wait' instead, or so?
> >>
> >> Looks better, or what about 'wait time'?
> > 
> > Works for me!
> 
> That column generically is time not running -- time between the last
> sched out and the current sched in. It could be expected (sleep,
> select, read, ...), waiting for a resource (disk I/O, mutex) or
> preemption.

Right.  Maybe it'd be better to show the prev_state as well to
identify the reason (roughly).

So, are you ok with the name 'wait time'?  My thinking is that they
are all waiting for something - timer, resource or cpu.

Thanks,
Namhyung

> 
> > 
> >> I'd go with the first option - simply adding arrows.  It's good enough to 
> >> identify each function IMHO.
> > 
> > Ok!
> 
> I'd prefer the arrows too for a default. Color can be an add-on option.