From: Jeremy Fitzhardinge Subject: Re: [PATCH V2 2/7] Cleancache (was Transcendent Memory): core files Date: Wed, 02 Jun 2010 17:21:05 -0700 Message-ID: <4C06F571.3050306@goop.org> References: <20100528173550.GA12219@ca-server1.us.oracle.com 20100602122900.6c893a6a.akpm@linux-foundation.org> <0be9e88e-7b0d-471d-8d49-6dc593dd43be@default> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Andrew Morton , chris.mason@oracle.com, viro@zeniv.linux.org.uk, adilger@Sun.COM, tytso@mit.edu, mfasheh@suse.com, joel.becker@oracle.com, matthew@wil.cx, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, ocfs2-devel@oss.oracle.com, linux-mm@kvack.org, ngupta@vflare.org, JBeulich@novell.com, kurt.hackel@oracle.com, npiggin@suse.de, dave.mccracken@oracle.com, riel@redhat.com, avi@redhat.com, konrad.wilk@oracle.com To: Dan Magenheimer Return-path: In-Reply-To: <0be9e88e-7b0d-471d-8d49-6dc593dd43be@default> Sender: owner-linux-mm@kvack.org List-Id: linux-ext4.vger.kernel.org On 06/02/2010 05:06 PM, Dan Magenheimer wrote: > It is intended that there be different flavours but only > one can be used in any running kernel. A driver file/module > claims the cleancache_ops pointer (and should check to ensure > it is not already claimed). And if nobody claims cleancache_ops, > the hooks should be as non-intrusive as possible. > > Also note that the operations occur on the order of the number > of I/O's, so definitely a lot, but "zillion" may be a bit high. :-) > > If you think this is a showstoppper, it could be changed > to be bound only at compile-time, but then (I think) the claimer > could never be a dynamically-loadable module. > Andrew is suggesting that rather than making cleancache_ops a pointer to a structure, just make it a structure, so that calling a function is a matter of cleancache_ops.func rather than cleancache_ops->func, thereby avoiding a pointer dereference. J -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org