From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261411AbVF0JFm (ORCPT ); Mon, 27 Jun 2005 05:05:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261960AbVF0JFm (ORCPT ); Mon, 27 Jun 2005 05:05:42 -0400 Received: from smtp200.mail.sc5.yahoo.com ([216.136.130.125]:12453 "HELO smtp200.mail.sc5.yahoo.com") by vger.kernel.org with SMTP id S261411AbVF0JEY (ORCPT ); Mon, 27 Jun 2005 05:04:24 -0400 Message-ID: <42BFC10E.50204@yahoo.com.au> Date: Mon, 27 Jun 2005 19:04:14 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.6) Gecko/20050324 Debian/1.7.6-1 X-Accept-Language: en MIME-Version: 1.0 To: Lincoln Dale CC: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [rfc] lockless pagecache References: <42BF9CD1.2030102@yahoo.com.au> <20050627004624.53f0415e.akpm@osdl.org> <42BFB287.5060104@yahoo.com.au> <42BFBF5B.7080301@cisco.com> In-Reply-To: <42BFBF5B.7080301@cisco.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Lincoln Dale wrote: > Nick Piggin wrote: > [..] > >> However I think for Oracle and others that use shared memory like >> this, they are probably not doing linear access, so that would be a >> net loss. I'm not completely sure (I don't have access to real loads >> at the moment), but I would have thought those guys would have looked >> into fault ahead if it were a possibility. > > > i thought those guys used O_DIRECT - in which case, wouldn't the page > cache not be used? > Well I think they do use O_DIRECT for their IO, but they need to use the Linux pagecache for their shared memory - that shared memory being the basis for their page cache. I think. Whatever the setup I believe they have issues with the tree_lock, which is why it was changed to an rwlock. -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com