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SubjectRe: pdflush eating a lot of CPU on heavy NFS I/O
On Wed, 28 Apr 2004, Andrew Morton wrote:

> Brent Cook <busterbcook@yahoo.com> wrote:
> >
> > On Tue, 27 Apr 2004, Andrew Morton wrote:
> >
> > > Brent Cook <busterbcook@yahoo.com> wrote:
>
> > > > the pdflush process starts using near 100% CPU indefinitely after
> > > > a few minutes of initial NFS traffic, as far as I can tell.
> > >
> > > Please confirm that the problem is observed on the NFS client and not the
> > > NFS server? I'll assume the client.
> >
> > Yes, both affected machines had the issue when connecting as a client to a
> > 2.4.25-based NFS server.
> >
> > > What other filesystems are in use on the client?
> >
> > One uses Reiser on /, the other uses ext3 on /. Here is the mount table
> > for one machine:
>
> Both machines are exhibiting the problem?

Yes. They both exhibit about 5-10 minutes after starting once I start
compiling from the NFS share. I'm going to also try a big compile from a
local directory to exercise the local FS to eliminate it as a possibility.

> > About 10 minutes into the process, pdflush starts taking over:
> >
> > PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME CPU COMMAND
> > 7 root 25 0 0 0 0 RW 34.4 0.0 3:05 0 pdflush
> > 17856 busterb 25 0 69400 65M 5140 R 34.4 26.1 0:31 0 cc1plus
> > 19466 busterb 25 0 43732 39M 5140 R 26.3 15.5 0:03 0 cc1plus
> > ...
> > The network light will flash continually on each machine once pdflush
> > gets into this state, which makes me think NFS. Each machine has
> > 512-256 MB of ram and a single CPU.
>
> ok.. I spent a couple of hours yesterday trying to get this to happen. No
> joy. Can't make it happen with your .config either. I'll set up a 2.4.25
> server later on.
>
> What version of gcc are you using?

3.3.3 previously. I just did a build with 3.4 with the same results; I'm
tracking Slackware-current, so my build environment reflects this.

> Could you please capture the contents of /proc/meminfo and /proc/vmstats
> when it's happening?

Will do. I can also provide a test account to you offline if it helps so
you can see it for yourself.

- Brent
-
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