From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263573AbTKJOoS (ORCPT ); Mon, 10 Nov 2003 09:44:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263775AbTKJOoR (ORCPT ); Mon, 10 Nov 2003 09:44:17 -0500 Received: from ns.virtualhost.dk ([195.184.98.160]:15332 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S263573AbTKJOoM (ORCPT ); Mon, 10 Nov 2003 09:44:12 -0500 Date: Mon, 10 Nov 2003 15:44:12 +0100 From: Jens Axboe To: Nick Piggin Cc: linux-kernel@vger.kernel.org, ckrm-tech@lists.sourceforge.net Subject: Re: [PATCH] cfq-prio #2 Message-ID: <20031110144412.GK32637@suse.de> References: <20031110140052.GC32637@suse.de> <3FAF9DAE.3070307@cyberone.com.au> <20031110142302.GF32637@suse.de> <3FAFA1E8.8080800@cyberone.com.au> <20031110143939.GJ32637@suse.de> <3FAFA401.5080404@cyberone.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3FAFA401.5080404@cyberone.com.au> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 11 2003, Nick Piggin wrote: > > > Jens Axboe wrote: > > >On Tue, Nov 11 2003, Nick Piggin wrote: > > > >> > >>You acked the change actually :P > >>I guess it was done in mainline when AS was merged. > >> > > > >Probably missed the semantic change of may_queue. > > > > Anyway I won't bother digging up the email, its been done now. Yeah too late to change now... > >>>>Maybe my version should be called elv_force_queue? > >>>> > >>>> > >>>I just hate to see more of these, really. The original idea for > >>>may_queue was just that, may this process queue io or not. We can make > >>>it return something else, though, to indicate whether the process must > >>>be able to queue. Is it really needed? > >>> > >>> > >>Its quite important. If the queue is full, and AS is waiting for a process > >>to submit a request, its got a long wait. > >> > >>Maybe a lower limit for per process nr_requests. Ie. you may queue if this > >>queue has less than 128 requests _or_ you have less than 8 requests > >>outstanding. This would solve my problem. It would also give you a much > >>more > >>appropriate scaling for server workloads, I think. Still, thats quite a > >>change in behaviour (simple to code though). > >> > > > >That basically belongs inside your may_queue for the io scheduler, imo. > > > > You can force it to disallow the request, but you can't force it to allow > one (depending on a successful memory allocation, of course). Well that's back two mails then, make may_queue return whether you must queue, may queue, or can't queue. -- Jens Axboe