Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264314AbUACWkS (ORCPT ); Sat, 3 Jan 2004 17:40:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264319AbUACWkS (ORCPT ); Sat, 3 Jan 2004 17:40:18 -0500 Received: from fw.osdl.org ([65.172.181.6]:6321 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S264314AbUACWkP (ORCPT ); Sat, 3 Jan 2004 17:40:15 -0500 Date: Sat, 3 Jan 2004 14:40:03 -0800 From: Andrew Morton To: Paolo Ornati Cc: gandalf@wlug.westbo.se, linuxram@us.ibm.com, linux-kernel@vger.kernel.org Subject: Re: Strange IDE performance change in 2.6.1-rc1 (again) Message-Id: <20040103144003.07cc10d9.akpm@osdl.org> In-Reply-To: <200401031213.01353.ornati@lycos.it> References: <200401021658.41384.ornati@lycos.it> <20040102213228.GH1882@matchmail.com> <1073082842.824.5.camel@tux.rsn.bth.se> <200401031213.01353.ornati@lycos.it> X-Mailer: Sylpheed version 0.9.4 (GTK+ 1.2.10; i686-pc-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 Content-Length: 1093 Lines: 26 Paolo Ornati wrote: > > I know these are only performance in sequential data reads... and real life > is another thing... but I think the author of the patch should be informed > (Ram Pai). There does seem to be something whacky going on with readahead against blockdevices. Perhaps it is related to the soft blocksize. I've never been able to reproduce any of this. Be aware that buffered reads for blockdevs are treated fairly differently from buffered reads for regular files: they only use lowmem and we always attach buffer_heads and perform I/O against them. No effort was made to optimise buffered blockdev reads because it is not very important and my main interest was in data coherency and filesystem metadata consistency. If you observe the same things reading from regular files then that is more important. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/