Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932494AbVJTRGS (ORCPT ); Thu, 20 Oct 2005 13:06:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932493AbVJTRGS (ORCPT ); Thu, 20 Oct 2005 13:06:18 -0400 Received: from ns.virtualhost.dk ([195.184.98.160]:19250 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S932494AbVJTRGR (ORCPT ); Thu, 20 Oct 2005 13:06:17 -0400 Date: Thu, 20 Oct 2005 19:07:06 +0200 From: Jens Axboe To: Tejun Heo Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH linux-2.6-block:master 02/05] blk: update ioscheds to use generic dispatch queue Message-ID: <20051020170705.GU2811@suse.de> References: <20051019123429.450E4424@htj.dyndns.org> <20051019123429.D377069C@htj.dyndns.org> <20051020112109.GC2811@suse.de> <20051020135124.GB26004@htj.dyndns.org> <20051020141104.GQ2811@suse.de> <4357AB3F.1050004@gmail.com> <20051020144108.GR2811@suse.de> <4357B10E.7010608@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4357B10E.7010608@gmail.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1562 Lines: 43 On Fri, Oct 21 2005, Tejun Heo wrote: > I think we're currently talking about two issues. I think so too :) > 1. Is @sort=0 case useful? > > Currently all ioscheds dispatch requests in sorted order. I was > afraid that sorting again might result in less efficient seek pattern > although I'm not quite sure whether or how that will happen. That's why > I added the @sort argument to elv_dispatch_insert(). If sorting cannot > hurt in any case, we might sort unconditionally and remove @sort > argument from elv_dispatch_insert(). That's what I ended up merging, elv_dispatch_sort() and it only takes q and rq as parameters. > 2. Why @force is used to turn on @sort? Yes, that was my question :-) > The reasoning was that, when a iosched is forced dispatched, it > doesn't have control over many aspects of IO scheduling, so it cannot > produce good ordering of dumped requests, which actually is true for > cfq. That's why @sort is turned on while force-dispatching requests. Well that's not quite my question, it is the opposite - why would you not want to sort? > Maybe just removing @sort argument from elv_dispatch_insert() and > sorting always is the way to go? See the merged stuff, I think so. I just don't see any reason at all to tie 'force' and 'sort' together. -- Jens Axboe - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/