linux-kernel - Re: Slab Fragmentation Reduction V15

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Message-ID: <alpine.DEB.2.00.1002011152510.30861@router.home>
Date:	Mon, 1 Feb 2010 11:53:52 -0600 (CST)
From:	Christoph Lameter <cl@...ux-foundation.org>
To:	Rik van Riel <riel@...hat.com>
cc:	Andi Kleen <andi@...stfloor.org>,
	Dave Chinner <david@...morbit.com>,
	Pekka Enberg <penberg@...helsinki.fi>,
	akpm@...ux-foundation.org, Miklos Szeredi <miklos@...redi.hu>,
	Nick Piggin <nickpiggin@...oo.com.au>,
	Hugh Dickins <hugh@...itas.com>, linux-kernel@...r.kernel.org,
	viro@...IV.linux.org.uk
Subject: Re: Slab Fragmentation Reduction V15

On Sat, 30 Jan 2010, Rik van Riel wrote:

> On 01/30/2010 05:48 AM, Andi Kleen wrote:
> > On Fri, Jan 29, 2010 at 02:49:31PM -0600, Christoph Lameter wrote:
>
> > > 	1. Establish a reference to an dentry/inode so that it is pinned.
> > >             Hopefully in a way that is not too expensive (i.e. no
> > > superblock
> > >             lock)
> > >
> > > 	2. A means to free a dentry/inode objects from the VM reclaim context.
> >
> >
> > Al, do you have a suggestions on a good way to do that?
>
> You cannot free inode objects for files that are open, mmapped, etc.

Of course. Those objects need to prevent reclaim attempts.

> > I guess the problem could be simplified by ignoring dentries in "unusual"
> > states?
>
> You mean dentries that are in use? :)

The existing patch already tried to discern that and avoid the reclaim of
these.

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