From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 10 Feb 2003 10:01:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 10 Feb 2003 10:01:59 -0500 Received: from cda1.e-mind.com ([195.223.140.107]:53122 "EHLO athlon.random") by vger.kernel.org with ESMTP id ; Mon, 10 Feb 2003 10:01:58 -0500 Date: Mon, 10 Feb 2003 16:11:44 +0100 From: Andrea Arcangeli To: Jens Axboe Cc: Linux Kernel Subject: Re: [PATCH] SFQ disk scheduler Message-ID: <20030210151144.GT31401@dualathlon.random> References: <20030210145001.GT12828@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20030210145001.GT12828@suse.de> User-Agent: Mutt/1.4i X-GPG-Key: 1024D/68B9CB43 X-PGP-Key: 1024R/CB4660B9 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 10, 2003 at 03:50:01PM +0100, Jens Axboe wrote: > Hi, > > Here's a simple stochastic fairness queueing disk scheduler, for current > 2.5.59-BK. It has known limitations right now, mainly because I didn't > bother making it complete. But it should suffice for some rudimentary > testing, at least. Cool, that was fast! ;) > > I'm not going to go into great detail about how it works, see Andrea's > initial post of the paper referenced. This version may not be completely > true to the SFQ concept, but should be close enough I think. It divides > traffic into a fixed number of buckets (64 per default), and perturbs > the hash every 5 seconds (hash shamelessly borrowed from networking atm, > see comment). I tend to think 5 seconds is too small, 30 sec would be better IMHO (it should be tested at bit). > To avoid too many disk seeks, when it's time to dispatch requests to the > driver, we round robin all non-empty buckets and grab a single request > from each. These requests are sorted into the dispatch queue. > > For performance reasons, io scheduler request merging is still a > per-queue function (and not per-bucket). Unsure if it worth, but it probably it won't make that much difference, likely different workloads are working on different part of the disk anyways. > In closing, let me stress that this version has not really been tested > all that much. It passes simple SCSI and IDE testing, should work on any > hardware basically. How does it feel? Andrea