From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262121AbULCJj4 (ORCPT ); Fri, 3 Dec 2004 04:39:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262125AbULCJj4 (ORCPT ); Fri, 3 Dec 2004 04:39:56 -0500 Received: from ns.virtualhost.dk ([195.184.98.160]:38102 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S262121AbULCJjf (ORCPT ); Fri, 3 Dec 2004 04:39:35 -0500 Date: Fri, 3 Dec 2004 10:39:03 +0100 From: Jens Axboe To: Andrew Morton Cc: "Prakash K. Cheemplavam" , linux-kernel@vger.kernel.org, nickpiggin@yahoo.com.au Subject: Re: Time sliced CFQ io scheduler Message-ID: <20041203093903.GE10492@suse.de> References: <20041202130457.GC10458@suse.de> <20041202134801.GE10458@suse.de> <20041202114836.6b2e8d3f.akpm@osdl.org> <20041202195232.GA26695@suse.de> <20041202121938.12a9e5e0.akpm@osdl.org> <41AF94B8.8030202@gmx.de> <20041203070108.GA10492@suse.de> <41B02DFD.9090503@gmx.de> <20041203012645.21377669.akpm@osdl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20041203012645.21377669.akpm@osdl.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 03 2004, Andrew Morton wrote: > "Prakash K. Cheemplavam" wrote: > > > > > Can you try with the patch that is in the parent of this thread? The > > > above doesn't look that bad, although read performance could be better > > > of course. But try with the patch please, I'm sure it should help you > > > quite a lot. > > > > > > > It actually got worse: Though the read rate seems accepteble, it is not, as > > interactivity is dead while writing. > > Is this a parallel IDE system? SATA? SCSI? If the latter, what driver > and what is the TCQ depth? Yeah, that would be interesting to know. Or of the device is on dm or raid. And what filesystem is being used? TCQ depth doesn't matter with cfq really, as you can fully control how big you go with the drive (default is 4) with max_depth. Running buffer reads and writes here with new cfq, I get about ~7MiB/sec read and ~14MiB/sec write aggregate performance with 4 clients (2 of each) with the default settings. If I up idle period to 6ms and slice period to 150ms, I get ~13MiB/sec read and ~11MiB/sec write aggregate for the same run. So Prakash, please try the same test with those settings: # cd /sys/block//queue/iosched # echo 6 > idle # echo 150 > slice These are the first I tried, there may be better settings. If you have your filesystem on dm/raid, you probably want to do the above for each device the dm/raid is composed of. -- Jens Axboe