From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757212AbYDQGOw (ORCPT ); Thu, 17 Apr 2008 02:14:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751862AbYDQGOo (ORCPT ); Thu, 17 Apr 2008 02:14:44 -0400 Received: from webmail1.posta.tim.it ([213.230.128.226]:14605 "EHLO fep05-svc.tim.it" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751619AbYDQGOn (ORCPT ); Thu, 17 Apr 2008 02:14:43 -0400 Message-ID: <4806EACB.7040408@unimore.it> Date: Thu, 17 Apr 2008 08:14:35 +0200 From: Paolo Valente User-Agent: Thunderbird 2.0.0.12 (Windows/20080213) MIME-Version: 1.0 To: Pavel Machek CC: axboe@kernel.dk, linux-kernel@vger.kernel.org Subject: Re: [RESEND][RFC] BFQ I/O Scheduler References: <20080401152903.GB34860@gandalf.sssup.it> <20080416184441.GA3923@ucw.cz> In-Reply-To: <20080416184441.GA3923@ucw.cz> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Pavel Machek ha scritto: > >> In the first type of tests, to achieve a higher throughput than CFQ >> (with the default 100 ms time slice), the maximum budget for BFQ >> had to be set to at least 4k sectors. Using the same value for the >> > > Hmm, 4k sectors is ~40 seconds worst case, no? That's quite long... > Actually, in the worst case among our tests, the aggregate throughput with 4k sectors was ~ 20 MB/s, hence the time for 4k sectors ~ 4k * 512 / 20M = 100 ms. About these test cases we repeated several measures of the aggregate throughput with simultaneous file reads from 2 to 5 (and other varying parameters). The lowest aggregate throughput for 4k sectors (~ 20 MB/s) was achieved in case of 2, 128 MB long, files, lying on two slices at the maximum distance from each other (more details on the experiments, testbed and so on at http://algo.ing.unimo.it/people/paolo/disk_sched/). I hope I didn't misunderstand your point.