Re: kupdated using all CPU

From: Eric W. Biederman (ebiederm@xmission.com)
Date: Mon Feb 18 2002 - 23:53:08 EST


Andrew Morton <akpm@zip.com.au> writes:

> john wrote:
> >
> > [Mon, Feb 18, 2002 at 02:13:06PM -0800] akpm@zip.com.au wrote:
> > + john wrote:
> > + >
> > + > hi,
> > + > ive searched all over and found many references to this problem, but
> > + > never found an actual solution. the problem is that during heavy
> > + > disk I/O, kupdated will periodically take up ALL the cpu.
> > +
> > + I've seen a couple of reports of this, nothing to indicate that it's
> > + a common problem?
> > +
> > + In the other reports, it was related to extremely low disk throughput.
> > + What does `hdparm -t /dev/hda' say?
> >
> > root@doom:~# hdparm -t /dev/hda
> >
> > /dev/hda:
> > Timing buffered disk reads: 64 MB in 25.60 seconds = 2.50 MB/sec
>
> ugh. OK, I'll see if I cen reproduce this - there's no reason
> why disk suckiness should cause high CPU load. But you need to
> pay some attention to your IDE settings in kernel config, and
> possibly tuning.

Another possibility with the same symptoms is that there are simply
very large I/O request starving everything else out. When some
crucial data needs to be paged back in. john can you confirm you
looked in top and saw kupdate taking 100% of the cpu?

Eric
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/



This archive was generated by hypermail 2b29 : Sat Feb 23 2002 - 21:00:18 EST