Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262246AbUKDPFK (ORCPT ); Thu, 4 Nov 2004 10:05:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262249AbUKDPFK (ORCPT ); Thu, 4 Nov 2004 10:05:10 -0500 Received: from lax-gate6.raytheon.com ([199.46.200.237]:11481 "EHLO lax-gate6.raytheon.com") by vger.kernel.org with ESMTP id S262246AbUKDPFD (ORCPT ); Thu, 4 Nov 2004 10:05:03 -0500 Subject: Re: [patch] Real-Time Preemption, -RT-2.6.10-rc1-mm2-V0.7.1 To: Ingo Molnar Cc: Karsten Wiese , Bill Huey , Adam Heath , "K.R. Foley" , linux-kernel@vger.kernel.org, Florian Schmidt , Fernando Pablo Lopez-Lezcano , Lee Revell , Rui Nuno Capela , Thomas Gleixner , Michal Schmidt X-Mailer: Lotus Notes Release 5.0.8 June 18, 2001 Message-ID: From: Mark_H_Johnson@raytheon.com Date: Thu, 4 Nov 2004 09:02:01 -0600 X-MIMETrack: Serialize by Router on RTSHOU-DS01/RTS/Raytheon/US(Release 6.5.2|June 01, 2004) at 11/04/2004 09:02:25 AM MIME-Version: 1.0 Content-type: text/plain; charset=US-ASCII X-SPAM: 0.00 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1805 Lines: 44 Let me follow up briefly on the regression I noticed yesterday on ping responses from an SMP system with one real time task running. Two systems were used for the tests, both dual 866 Mhz Pentium III systems, identical except for the software. The "old" machine is running Red Hat 7.3 with a 2.4.24 preempt, low latency kernel. The "new" machine is running Fedora Core 2 with a 2.6 kernel as indicated below. The other difference that may be significant is the "old" system uses OSS and the new one uses ALSA for the audio output (source of latencytest application is unchanged for all three tests). The data below is from using another machine to ping the system under test. 2.4.24 preempt + low latency on "old" machine 430 seconds for the complete series of tests 0 lost packets 0.248, 0.322, 2.82, 0.145 (min, average, max, deviation) 2.6.5-1.358smp [from fedora core 2] on "new" machine 658 seconds for the complete series of tests 0 lost packets 0.148, 0.207, 1.952, 0.097 (min, average, max, deviation) This system also lost the mouse (screaming interrupts, IRQ 10 disabled). 2.6.9-rc3-mm3-VP-T3 on "new machine" 955 seconds for the complete series of tests 539 lost packets 0.215, 17971, 287799, 63054 (min, average, max, deviation) I did not repeat the tests on -V0.7.7, but I expect them to come out similar to -T3 above based on what I saw yesterday. In any case, the loss of network data appears significant with both the voluntary preempt & realtime preempt patches on 2.6 kernels. --Mark H Johnson - 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/