From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261484AbVGCSQL (ORCPT ); Sun, 3 Jul 2005 14:16:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261486AbVGCSQL (ORCPT ); Sun, 3 Jul 2005 14:16:11 -0400 Received: from mx1.elte.hu ([157.181.1.137]:51370 "EHLO mx1.elte.hu") by vger.kernel.org with ESMTP id S261484AbVGCSMp (ORCPT ); Sun, 3 Jul 2005 14:12:45 -0400 Date: Sun, 3 Jul 2005 20:12:29 +0200 From: Ingo Molnar To: William Weston Cc: linux-kernel@vger.kernel.org Subject: Re: Real-Time Preemption, -RT-2.6.12-final-V0.7.50-24 Message-ID: <20050703181229.GA32741@elte.hu> References: <200506281927.43959.annabellesgarden@yahoo.de> <200506301952.22022.annabellesgarden@yahoo.de> <20050630205029.GB1824@elte.hu> <200507010027.33079.annabellesgarden@yahoo.de> <20050701071850.GA18926@elte.hu> <20050703140432.GA19074@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050703140432.GA19074@elte.hu> User-Agent: Mutt/1.4.2.1i X-ELTE-SpamVersion: MailScanner 4.31.6-itk1 (ELTE 1.2) SpamAssassin 2.63 ClamAV 0.73 X-ELTE-VirusStatus: clean X-ELTE-SpamCheck: no X-ELTE-SpamCheck-Details: score=-4.9, required 5.9, autolearn=not spam, BAYES_00 -4.90 X-ELTE-SpamLevel: X-ELTE-SpamScore: -4 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Ingo Molnar wrote: > > A few things are left working (but not enough to get the system back): > > > > - Mouse pointer (movements are chunky) and window focus. > > - Mouse scroll wheel can still scroll xterms and switch workspaces. > > - SysRq-B > > hm, i can reproduce a variant of this, by starting enough 'dd' tasks. > (it needed more than two on a 2-way/4-way HT testbox though) Indeed > everything seems to be starved, but SysRq still worked so i was able > to SysRq-kIll all tasks and thus the system recovered. > > i'm debugging this now. ok, found a bug that could explain the situation: mutex sleeps+wakeups were incorrectly credited as 'interactive sleep' periods, causing the dd processes to be boosted incorrectly. The dd processes created a workload in which they blocked each other in such a pattern that they got boosted periodically, starving pretty much every other task. the fix is significant and affects alot of workloads, and should further improve interactivity in noticeable ways. I'm not 100% sure it solves all the starvation problems (e.g. how could normal-prio dd tasks starve the SCHED_FIFO irq threads that drove SysRq?), but the results so far look promising. i've uploaded the -50-45 patch, can you under this kernel trigger a 'meltdown' on your SMT box? Ingo