From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S272454AbTHEGLJ (ORCPT ); Tue, 5 Aug 2003 02:11:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S272455AbTHEGLJ (ORCPT ); Tue, 5 Aug 2003 02:11:09 -0400 Received: from anumail3.anu.edu.au ([150.203.2.43]:6324 "EHLO anu.edu.au") by vger.kernel.org with ESMTP id S272454AbTHEGLF (ORCPT ); Tue, 5 Aug 2003 02:11:05 -0400 Message-ID: <3F2F4076.1030009@cyberone.com.au> Date: Tue, 05 Aug 2003 15:28:22 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; SunOS sun4u; en-US; rv:1.2.1) Gecko/20021217 MIME-Version: 1.0 To: Con Kolivas CC: linux kernel mailing list , Andrew Morton , Ingo Molnar , Felipe Alfaro Solana Subject: Re: [PATCH] O13int for interactivity References: <200308050207.18096.kernel@kolivas.org> <200308051220.04779.kernel@kolivas.org> <3F2F149F.1020201@cyberone.com.au> <200308051318.47464.kernel@kolivas.org> <3F2F2517.7080507@cyberone.com.au> <1060059844.3f2f3ac46e2f2@kolivas.org> <3F2F3CC6.2060307@cyberone.com.au> <1060060568.3f2f3d989683f@kolivas.org> In-Reply-To: <1060060568.3f2f3d989683f@kolivas.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Sender-Domain: cyberone.com.au X-Spam-Score: (-2.8) X-Spam-Tests: DATE_IN_PAST_06_12,EMAIL_ATTRIBUTION,IN_REP_TO,REFERENCES,SPAM_PHRASE_02_03,USER_AGENT,USER_AGENT_MOZILLA_UA Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Con Kolivas wrote: >Quoting Nick Piggin : > snip > >>Oh, I'm not saying that your change is outright wrong, on the contrary I'd >>say you have a better feel for what is needed than I do, but if you are >>finding >>that the uninterruptible sleep case needs some tweaking then the same tweak >>should be applied to all sleep cases. If there really is a difference, >>then its >>just a fluke that the sleep paths in question use the type of sleep you are >>testing for, and nothing more profound than that. >> > >Ah I see. It was from my observations of the behaviour of tasks in D that >found it was the period spent in D that was leading to unfairness. The same >tweak can't be applied to the rest of the sleeps because that inactivates >everything. So it is a fluke that the thing I'm trying to penalise is what >tasks in uninterruptible sleep do, but it is by backward observation of D >tasks, not random chance. > Yes yes, but we come to the same conclusion no matter why you have decided to make the change ;) namely that you're only papering over a flaw in the scheduler! What happens in the same sort of workload that is using interruptible sleeps? Say the same make -j NFS mounted interrruptible (I think?). I didn't really understand your answer a few emails ago... please just reiterate: if the problem is that processes sleeping too long on IO get too high a priority, then give all processes the same boost after they have slept for half a second? Also, why is this a problem exactly? Is there a difference between a process that would be a CPU hog but for its limited disk bandwidth, and a process that isn't a CPU hog? Disk IO aside, they are exactly the same thing to the CPU scheduler, aren't they? _wants_ to be a CPU hog, but can't due to disk