From: Pavel Machek <pavel@ucw.cz>
To: Al Boldi <a1426z@gawab.com>
Cc: Jan Engelhardt <jengelh@linux01.gwdg.de>, linux-kernel@vger.kernel.org
Subject: Re: Incorrect CPU process accounting using CONFIG_HZ=100
Date: Mon, 26 Jun 2006 18:02:39 +0200 [thread overview]
Message-ID: <20060626160239.GA3257@elf.ucw.cz> (raw)
In-Reply-To: <200606222036.39908.a1426z@gawab.com>
On Thu 2006-06-22 20:36:39, Al Boldi wrote:
> Jan Engelhardt wrote:
> > >Setting CONFIG_HZ=100 results in incorrect CPU process accounting.
> > >
> > >This can be seen running top d.1, that shows top, itself, consuming 0ms
> > >CPUtime.
> > >
> > >Will this bug have consequences for sched.c?
> >
> > Works for me, somewhat.
> > TIME+ says 0:00.02 after 70 secs. (Ergo: top is not expensive on this
> > CPU.)
>
> That's what I thought for a long time. But at closer inspection, top d.1
> slows down other apps by about the same amount of time at 1000Hz and 100Hz,
> only at 1000Hz it is accounted for whereas at 100Hz it is not.
It is not a bug... it is design decision. If you eat "too little" cpu
time, you'll be accouted 0 msec. That's what happens at 100Hz...
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
next prev parent reply other threads:[~2006-06-26 16:02 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-21 14:16 Incorrect CPU process accounting using CONFIG_HZ=100 Al Boldi
2006-06-22 5:46 ` Jan Engelhardt
2006-06-22 17:36 ` Al Boldi
2006-06-26 16:02 ` Pavel Machek [this message]
2006-06-27 12:32 ` Al Boldi
2006-06-27 13:02 ` Con Kolivas
2006-06-27 23:52 ` Peter Williams
2006-06-28 20:06 ` Al Boldi
2006-06-28 23:23 ` Peter Williams
2006-06-28 23:46 ` Con Kolivas
2006-06-29 0:25 ` Peter Williams
2006-06-29 1:10 ` Con Kolivas
2006-06-29 7:29 ` Pavel Machek
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