From mboxrd@z Thu Jan  1 00:00:00 1970
From: =?utf-8?B?SsO2cm4=?= Engel <joern@logfs.org>
Subject: Re: vm/fs meetup details
Date: Mon, 9 Jul 2007 02:27:21 +0200
Message-ID: <20070709002720.GA13081@lazybastard.org>
References: <20070705040138.GG32240@wotan.suse.de> <468D303E.4040902@redhat.com> <20070706020042.GD14215@wotan.suse.de> <Pine.LNX.4.64.0707061339100.24812@schroedinger.engr.sgi.com> <20070707104534.GA5686@lazybastard.org> <20070708232938.GG12413810@sgi.com>
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Cc: =?utf-8?B?SsO2cm4=?= Engel <joern@logfs.org>,
	Christoph Lameter <clameter@sgi.com>,
	Nick Piggin <npiggin@suse.de>, Rik van Riel <riel@redhat.com>,
	Anton Altaparmakov <aia21@cam.ac.uk>,
	Suparna Bhattacharya <suparna@in.ibm.com>,
	Christoph Hellwig <hch@infradead.org>,
	Zach Brown <zach.brown@oracle.com>,
	Hugh Dickins <hugh@veritas.com>,
	Jared Hulbert <jaredeh@gmail.com>,
	Chris Mason <chris.mason@oracle.com>,
	"Martin J. Bligh" <mbligh@mbligh.org>,
	Trond Myklebust <trond.myklebust@fys.uio.no>,
	Neil Brown <neilb@suse.de>, Miklos Szeredi <miklos@szeredi.hu>,
	Mingming Cao <cmm@us.ibm.com>,
	Linux Memory Management List <linux-mm@kvack.org>,
	linux-fsdevel@vger.kernel.org
To: David Chinner <dgc@sgi.com>
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On Mon, 9 July 2007 09:29:38 +1000, David Chinner wrote:
> On Sat, Jul 07, 2007 at 12:45:35PM +0200, J=C3=83=C2=B6rn Engel wrote=
:
> >=20
> > Oh certainly!  I should dust off my dcache_static patch.  Some dent=
ries
> > are hands-off for the shrinker, basically mountpoints and tmpfs.  T=
he
> > patch moves those to a seperate slab cache.
>=20
> I doubt there's enough of those to make any difference - putting all
> the directories into another slab did little to reduce fragmentation
> (~18 months ago we tried that), so I don't think that this would help
> at all...

Interesting.  I suspect that the de-facto random cache eviction has a
bigger effect and overshadows everything else.  So the decisive step
would be to nuke all dentries in a given slab.

It wouldn't surprise me if your patch did make a difference afterwards.
With 32 dentries per slab, it doesn't take many pinned objects to pin
most slabs.

J=C3=B6rn

--=20
All art is but imitation of nature.
-- Lucius Annaeus Seneca
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