From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932243AbWAPIIP (ORCPT ); Mon, 16 Jan 2006 03:08:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932229AbWAPIIP (ORCPT ); Mon, 16 Jan 2006 03:08:15 -0500 Received: from c-67-177-35-222.hsd1.ut.comcast.net ([67.177.35.222]:11649 "EHLO ns1.utah-nac.org") by vger.kernel.org with ESMTP id S932243AbWAPIIO (ORCPT ); Mon, 16 Jan 2006 03:08:14 -0500 Message-ID: <43CB4C03.7070304@wolfmountaingroup.com> Date: Mon, 16 Jan 2006 00:32:19 -0700 From: "Jeff V. Merkey" User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040510 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Max Waterman Cc: linux-kernel@vger.kernel.org Subject: Re: io performance... References: <43CB4CC3.4030904@fastmail.co.uk> In-Reply-To: <43CB4CC3.4030904@fastmail.co.uk> Content-Type: multipart/mixed; boundary="------------020908010604050004060206" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org This is a multi-part message in MIME format. --------------020908010604050004060206 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Max Waterman wrote: > Hi, > > I've been referred to this list from the linux-raid list. > > I've been playing with a RAID system, trying to obtain best bandwidth > from it. > > I've noticed that I consistently get better (read) numbers from kernel > 2.6.8 > than from later kernels. To open the bottlenecks, the following works well. Jens will shoot me for recommending this, but it works well. 2.6.9 so far has the highest numbers with this fix. You can manually putz around with these numbers, but they are an artificial constraint if you are using RAID technology that caches ad elevators requests and consolidates them. Jeff --------------020908010604050004060206 Content-Type: text/x-patch; name="blkdev.patch" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="blkdev.patch" diff -Naur ./include/linux/blkdev.h ../linux-2.6.9/./include/linux/blkdev.h --- ./include/linux/blkdev.h 2004-10-18 15:53:43.000000000 -0600 +++ ../linux-2.6.9/./include/linux/blkdev.h 2005-12-06 09:54:46.000000000 -0700 @@ -23,8 +23,10 @@ typedef struct elevator_s elevator_t; struct request_pm_state; -#define BLKDEV_MIN_RQ 4 -#define BLKDEV_MAX_RQ 128 /* Default maximum */ +//#define BLKDEV_MIN_RQ 4 +//#define BLKDEV_MAX_RQ 128 /* Default maximum */ +#define BLKDEV_MIN_RQ 4096 +#define BLKDEV_MAX_RQ 8192 /* Default maximum */ --------------020908010604050004060206--