From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268236AbUHFSKy (ORCPT ); Fri, 6 Aug 2004 14:10:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S266073AbUHFSKl (ORCPT ); Fri, 6 Aug 2004 14:10:41 -0400 Received: from fecls-02.atlarge.net ([129.41.63.107]:32835 "HELO fecls-02.atlarge.net") by vger.kernel.org with SMTP id S266561AbUHFSIb (ORCPT ); Fri, 6 Aug 2004 14:08:31 -0400 Message-ID: <4113C7BA.6060608@cse.wustl.edu> Date: Fri, 06 Aug 2004 13:02:34 -0500 From: "Mr. Berkley Shands" User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7) Gecko/20040616 X-Accept-Language: en-us, en MIME-Version: 1.0 To: linux-kernel@vger.kernel.org Subject: Fast patch for Severe I/O performance regression 2.6.6 to 2.6.7 or 2.6.8-rc3 References: <41126811.7020607@dssimail.com> <20040805172531.GC17188@holomorphy.com> In-Reply-To: <20040805172531.GC17188@holomorphy.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 06 Aug 2004 18:04:05.0022 (UTC) FILETIME=[C2DA33E0:01C47BDF] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org in 2.6.8-rc3/mm/readahead.c line 475 (about label do_io:) #if 0 ra->next_size = min(average , (unsigned long)max); #endif the comment for the above is here after an lseek. The lseek IS inside the window, but the code will always destroy the window and start again. The above patch corrects the performance problem, but it would be better to do nothing if the lseek is still within the read ahead window. berkley