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Date: Thu, 19 Sep 2002 22:44:36 +0100
From: "Stephen C. Tweedie" <sct@redhat.com>
To: Andrew Morton <akpm@digeo.com>
Cc: Duncan Sands <duncan.sands@math.u-psud.fr>,
       lkml <linux-kernel@vger.kernel.org>,
       "ext2-devel@lists.sourceforge.net" <ext2-devel@lists.sourceforge.net>
Subject: Re: [Ext2-devel] Re: fsync 50 times slower after 2.5.27
Message-ID: <20020919224436.E2831@redhat.com>
References: <200209190222.33276.duncan.sands@math.u-psud.fr> <3D891BD1.8F774946@digeo.com> <200209192032.25933.duncan.sands@math.u-psud.fr> <3D8A4016.F364B303@digeo.com>
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In-Reply-To: <3D8A4016.F364B303@digeo.com>; from akpm@digeo.com on Thu, Sep 19, 2002 at 02:22:30PM -0700
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Hi,

On Thu, Sep 19, 2002 at 02:22:30PM -0700, Andrew Morton wrote:

> Thanks for testing.  The semantics of sched_yield() have changed
> significantly in 2.5.  Probably correctly, but it is breaking a
> few things which were tuned for the old semantics.  Amongst those
> things are OpenOffice and, it seems, ext3 transaction batching.
> 
> The transaction batching does good things under some situations,
> and we want it to keep working.  I'll sit tight for the while, see
> where shed_yield() behaviour ends up.  If we still have a problem
> then probably a schedule_timeout(1) in there would suffice.

Actually, with a proper yield() implementation, we can achieve the
same effect by making the commit thread do the yield itself before
locking down the transaction.  Having _every_ sync thread do a yield
itself before calling for a commit is probably overkill.

--Stephen
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