Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752055AbWAEGcF (ORCPT ); Thu, 5 Jan 2006 01:32:05 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752058AbWAEGcF (ORCPT ); Thu, 5 Jan 2006 01:32:05 -0500 Received: from mail.gmx.net ([213.165.64.21]:24772 "HELO mail.gmx.net") by vger.kernel.org with SMTP id S1752055AbWAEGcE (ORCPT ); Thu, 5 Jan 2006 01:32:04 -0500 X-Authenticated: #14349625 Message-Id: <5.2.1.1.2.20060105070601.026b21f0@pop.gmx.net> X-Mailer: QUALCOMM Windows Eudora Version 5.2.1 Date: Thu, 05 Jan 2006 07:31:51 +0100 To: Peter Williams , Helge Hafting From: Mike Galbraith Subject: Re: [PATCH] sched: Fix adverse effects of NFS client on interactive response Cc: Trond Myklebust , Ingo Molnar , Con Kolivas , Linux Kernel Mailing List In-Reply-To: <43BC4353.3090704@bigpond.net.au> References: <43BB2414.6060400@bigpond.net.au> <43A8EF87.1080108@bigpond.net.au> <1135145341.7910.17.camel@lade.trondhjem.org> <43A8F714.4020406@bigpond.net.au> <20060102110145.GA25624@aitel.hist.no> <43B9BD19.5050408@bigpond.net.au> <43BB2414.6060400@bigpond.net.au> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed X-Antivirus: avast! (VPS 0601-0, 01/02/2006), Outbound message X-Antivirus-Status: Clean X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1312 Lines: 26 At 08:51 AM 1/5/2006 +1100, Peter Williams wrote: >I think that some of the harder to understand parts of the scheduler code >are actually attempts to overcome the undesirable effects (such as those >I've described) of inappropriately identifying tasks as interactive. I >think that it would have been better to attempt to fix the inappropriate >identifications rather than their effects and I think the prudent use of >TASK_NONINTERACTIVE is an important tool for achieving this. IMHO, that's nothing but a cover for the weaknesses induced by using exclusively sleep time as an information source for the priority calculation. While this heuristic does work pretty darn well, it's easily fooled (intentionally or otherwise). The challenge is to find the right low cost informational component, and to stir it in at O(1). The fundamental problem with the whole interactivity issue is that the kernel has no way to know if there's a human involved or not. My 100%cpu GL screensaver is interactive while I'm mindlessly staring at it. -Mike - 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/