From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264278AbUEDLkN (ORCPT ); Tue, 4 May 2004 07:40:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264312AbUEDLkN (ORCPT ); Tue, 4 May 2004 07:40:13 -0400 Received: from smtp101.mail.sc5.yahoo.com ([216.136.174.139]:26543 "HELO smtp101.mail.sc5.yahoo.com") by vger.kernel.org with SMTP id S264278AbUEDLkJ (ORCPT ); Tue, 4 May 2004 07:40:09 -0400 Message-ID: <40978108.3020600@yahoo.com.au> Date: Tue, 04 May 2004 21:39:52 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040401 Debian/1.6-4 X-Accept-Language: en MIME-Version: 1.0 To: Andrew Morton CC: peter@mysql.com, linuxram@us.ibm.com, alexeyk@mysql.com, linux-kernel@vger.kernel.org, axboe@suse.de Subject: Re: Random file I/O regressions in 2.6 References: <200405022357.59415.alexeyk@mysql.com> <409629A5.8070201@yahoo.com.au> <20040503110854.5abcdc7e.akpm@osdl.org> <1083615727.7949.40.camel@localhost.localdomain> <20040503135719.423ded06.akpm@osdl.org> <1083620245.23042.107.camel@abyss.local> <20040503145922.5a7dee73.akpm@osdl.org> <4096DC89.5020300@yahoo.com.au> <20040503171005.1e63a745.akpm@osdl.org> <4096E1A6.2010506@yahoo.com.au> <20040503181533.59af9762.akpm@osdl.org> In-Reply-To: <20040503181533.59af9762.akpm@osdl.org> 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 Andrew Morton wrote: > > > Sorry, I do not understand that paragraph at all. > > All forms or pagecache population need to examine the pagecache to find out > if the page is already there. This involves pagecache lookups. We want > the read code to "learn" that the requested pages are all coming from cache > and to stop doing those lookups altogether. Yeah I think I have an idea of what the basic problems are, but I'd have to understand things better before I know if I am really on the right track. My idea would probably also involve redoing some of the code code too, so at the moment I don't think I have time. If your simple fix works though, then that sounds good.