From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261622AbULBNsb (ORCPT ); Thu, 2 Dec 2004 08:48:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261621AbULBNsb (ORCPT ); Thu, 2 Dec 2004 08:48:31 -0500 Received: from ns.virtualhost.dk ([195.184.98.160]:23239 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S261622AbULBNs3 (ORCPT ); Thu, 2 Dec 2004 08:48:29 -0500 Date: Thu, 2 Dec 2004 14:48:02 +0100 From: Jens Axboe To: Linux Kernel Cc: Nick Piggin Subject: Re: Time sliced CFQ io scheduler Message-ID: <20041202134801.GE10458@suse.de> References: <20041202130457.GC10458@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20041202130457.GC10458@suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, One more test case, while the box is booted... This just demonstrates a process doing a file write (bs=64k) with a competing process doing a file read (bs=64k) at the same time, again capped at 30sec. deadline: Reader: 2520KiB/sec (max_lat=45msec) Writer: 1258KiB/sec (max_lat=85msec) as: Reader: 27985KiB/sec (max_lat=34msec) Writer: 64KiB/sec (max_lat=1042msec) cfq: Reader: 12703KiB/sec (max_lat=108msec) Writer: 9743KiB/sec (max_lat=89msec) If you look at vmstat while running these tests, cfq and deadline give equal bandwidth for the reader and writer all the time, while as basically doesn't give anything to the writer (a single block per second only). Nick, is the write batching broken or something? -- Jens Axboe