Re: [patch 1/3] add basic accounting fields to taskstats

[Al Boldi <a1426z@gawab.com>]

Balbir Singh wrote:
> Jay Lan wrote:
> > I figured this out. The tsk->stime (and utime as well) are
> > charged by 1 tick (or cputime) from the timer interrupt handler
> > through update_process_times->account_{user,system}_time.
> >
> > The clock resolution is a tick. Any short process less than
> > 1 tick will the counter being 0. It can be from 0 to 0.99999...
> > tick. A half tick is the average value.
>
> But the scheduling happens in the granularity of a tick, so the minimum
> each task gets is a tick.
>
> > I think it makes more sense to assign a half tick than assign
> > 1 usec to the stime. What do you think? Certainly the code need
> > better explanation.
>
> Can't we leave these values as zero in case both stime and utime are zero.

FYI, see "Incorrect CPU process accounting using CONFIG_HZ=100" thread.

IMHO, in-lined process accounting is probably critical for successful 
scheduling.

Thanks!

--
Al

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