Subject: Re: kmail slowdown on 2.6.* +reiserFS (v3)
From: Chris Mason <mason@suse.com>
To: Andrew Morton <akpm@osdl.org>
Cc: linux-kernel@vger.kernel.org, reiserfs-dev@namesys.com
In-Reply-To: <20040111182739.0686fbee.akpm@osdl.org>
References: <200401112109.22027.ciaby@autistici.org>
	 <20040111182739.0686fbee.akpm@osdl.org>
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Date: Wed, 14 Jan 2004 08:20:46 -0500
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On Sun, 2004-01-11 at 21:27, Andrew Morton wrote:
> Ciaby <ciaby@autistici.org> wrote:
> >
> > I all!
> > I've recently upgraded from 2.4 to 2.6 and I've noticed a strange thing:
> > on the 2.4 kernel, kmail run decently (i've an old k6-200).
> > On the 2.6 kernel, kmail slowdown and take a very long time to read a mailbox.
> > I think something changed in the reiserFS during this time...
> > I'm not the only experiencing this problem, read this:
> > http://kerneltrap.org/node/view/1844
> 
> A buglet in kmail was tripped up by some optimisations which went into
> reiserfs.
> 
> Upgrading kmail should fix it up.  Or mount the reiserfs filesystems with
> the `nolargeio=1' mount option.

Actually, we've hit other problems with v3 largeio, it can confuse rpm
badly.  The real bug is apparently in bdb, the larger io size suggested
by the filesystem lead bdb to corrupt its own files.  I spent some time
neck deep in the db code but couldn't track the problem down.

I seem to remember the XFS folks hitting exactly the same bug.

Hans, can I talk you into having v3 export an io size of 4k to userspace
again?  Applications that send large ios would still use Oleg's
optimized file write paths.

-chris


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