Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261622AbUKXA7x (ORCPT ); Tue, 23 Nov 2004 19:59:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261385AbUKXA7i (ORCPT ); Tue, 23 Nov 2004 19:59:38 -0500 Received: from viper.oldcity.dca.net ([216.158.38.4]:44264 "HELO viper.oldcity.dca.net") by vger.kernel.org with SMTP id S261622AbUKXA6Z (ORCPT ); Tue, 23 Nov 2004 19:58:25 -0500 Subject: Re: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm2-V0.7.30-9 From: Lee Revell To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Rui Nuno Capela , Mark_H_Johnson@Raytheon.com, "K.R. Foley" , Bill Huey , Adam Heath , Florian Schmidt , Thomas Gleixner , Michal Schmidt , Fernando Pablo Lopez-Lezcano , Karsten Wiese , Gunther Persoons , emann@mrv.com, Shane Shrybman , Amit Shah , Esben Nielsen In-Reply-To: <20041123175823.GA8803@elte.hu> References: <20041109160544.GA28242@elte.hu> <20041111144414.GA8881@elte.hu> <20041111215122.GA5885@elte.hu> <20041116125402.GA9258@elte.hu> <20041116130946.GA11053@elte.hu> <20041116134027.GA13360@elte.hu> <20041117124234.GA25956@elte.hu> <20041118123521.GA29091@elte.hu> <20041118164612.GA17040@elte.hu> <20041122005411.GA19363@elte.hu> <20041123175823.GA8803@elte.hu> Content-Type: text/plain Date: Tue, 23 Nov 2004 19:58:23 -0500 Message-Id: <1101257903.13780.15.camel@krustophenia.net> Mime-Version: 1.0 X-Mailer: Evolution 2.0.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1768 Lines: 41 On Tue, 2004-11-23 at 18:58 +0100, Ingo Molnar wrote: > i have released the -V0.7.30-9 Real-Time Preemption patch, which can be > downloaded from the usual place: > > http://redhat.com/~mingo/realtime-preempt/ I have notices some weird interactivity issues with this. These are also present in T3. The symptom is that CPU bound tasks like kernel compiles will starve I/O bound tasks like evolution for a _long_ time. If I have a kernel build and external modules building at the same time and Evolution goes to "Update message list...", it can sit and spin with a blank message pane for a minute or two. If I suspend the builds, the message list renders immediately. It seems like the build process is constantly preempting the Evolution process, preventing the latter from making much progress. The build on the other hand progresses fine. AIUI I/O bound, interactive tasks like a mail client should get scheduled in preference to CPU bound tasks like builds. The scheduler has heuristics to distinguish the two types of tasks and boosts the dynamic priority of the former, right? It seems like exactly the opposite is happening. Another possibility is that Evolution really DOES use so many cycles to generate the message list that it looks like a CPU bound process to the kernel. Unfortunately I think this seems most likely. For example, evolution still consumes a hell of a lot of CPU at a low nice value. It just makes other tasks stall this way. Do I need to just find a better mail client? Lee - 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/