From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261728AbULDQGV (ORCPT ); Sat, 4 Dec 2004 11:06:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261730AbULDQGV (ORCPT ); Sat, 4 Dec 2004 11:06:21 -0500 Received: from vsmtp1.tin.it ([212.216.176.141]:60038 "EHLO vsmtp1.tin.it") by vger.kernel.org with ESMTP id S261728AbULDQGS (ORCPT ); Sat, 4 Dec 2004 11:06:18 -0500 Date: Sat, 4 Dec 2004 14:05:01 +0100 From: Giuliano Pochini To: Jens Axboe Cc: linux-kernel@vger.kernel.org Subject: Re: Time sliced CFQ io scheduler Message-Id: <20041204140501.52fddd94.pochini@shiny.it> In-Reply-To: <20041202144129.GI10458@suse.de> References: <20041202130457.GC10458@suse.de> <20041202144129.GI10458@suse.de> X-Mailer: Sylpheed version 0.9.6 (GTK+ 1.2.10; powerpc-unknown-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 On Thu, 2 Dec 2004 15:41:34 +0100 Jens Axboe wrote: > > > Case 4: write_files, random, bs=4k > > > > Just a thought... in this test the results don't look right. Why > > aggregate bandwidth with 8 clients is higher than with 4 and 2 clients ? > > In the cfq test with 8 clients aggregate bw is also higher than with > > a single client. > > I don't know what happens with the 4 client case, but it's not that > unlikely that aggregate bandwidth will be higher for more threads doing > random writes, as request coalesching will help minimize seeks. In order to keep the probabilty that requests get coalesced constant, the size of the test file should be multiple of the number of clients. -- Giuliano.