From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261685AbUE3ExV (ORCPT ); Sun, 30 May 2004 00:53:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261712AbUE3ExV (ORCPT ); Sun, 30 May 2004 00:53:21 -0400 Received: from fw.osdl.org ([65.172.181.6]:4582 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S261685AbUE3ExT (ORCPT ); Sun, 30 May 2004 00:53:19 -0400 Date: Sat, 29 May 2004 21:52:26 -0700 From: Andrew Morton To: Doug Ledford Cc: antlarr@tedial.com, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org Subject: Re: iowait problems on 2.6, not on 2.4 Message-Id: <20040529215226.68605319.akpm@osdl.org> In-Reply-To: <1085877991.18642.336.camel@compaq.xsintricity.com> References: <200405261743.28111.antlarr@tedial.com> <20040526205225.7a0866aa.akpm@osdl.org> <200405281516.41901.antlarr@tedial.com> <20040528154525.6ed5f7b9.akpm@osdl.org> <1085877991.18642.336.camel@compaq.xsintricity.com> X-Mailer: Sylpheed version 0.9.7 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Doug Ledford wrote: > > But, I could be wrong. Give it a try and see what happens. In the 2.4 > kernels I would tell you to tweak /proc/sys/vm/{min,max}-readahead, > don't know if those two knobs still exist in 2.6 and if they have the > same effect. Andrew? blockdev --setra N /dev/sda (N is in 512 byte units) echo N > /sys/block/sda/queue/read_ahead_kb (N is in kilobytes) Also there was breakage (recently fixed) in which /dev/sdaN's readahead setting was being inherited from the blockdev on which /dev resides. But reading regular files is OK.