From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261593AbULIT3d (ORCPT ); Thu, 9 Dec 2004 14:29:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261595AbULIT3d (ORCPT ); Thu, 9 Dec 2004 14:29:33 -0500 Received: from dfw-gate3.raytheon.com ([199.46.199.232]:1379 "EHLO dfw-gate3.raytheon.com") by vger.kernel.org with ESMTP id S261593AbULIT3V (ORCPT ); Thu, 9 Dec 2004 14:29:21 -0500 Subject: Re: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm3-V0.7.32-6 To: Ingo Molnar Cc: Amit Shah , Karsten Wiese , Bill Huey , Adam Heath , emann@mrv.com, Gunther Persoons , "K.R. Foley" , linux-kernel@vger.kernel.org, Florian Schmidt , Fernando Pablo Lopez-Lezcano , Lee Revell , Rui Nuno Capela , Shane Shrybman , Esben Nielsen , 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, 9 Dec 2004 12:15:41 -0600 X-MIMETrack: Serialize by Router on RTSHOU-DS01/RTS/Raytheon/US(Release 6.5.2|June 01, 2004) at 12/09/2004 12:15:43 PM 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 >* Mark_H_Johnson@raytheon.com wrote: > >> >also, i'd like to take a look at latency traces, if you have them for >> >this run. >> >> I could if I had any. The _RT run had NO latency traces > 250 usec >> (the limit I had set for the test). The equivalent _PK run had 37 of >> those traces. I can rerun the test with a smaller limit to get some if >> it is really important. My build of -12 is almost done and we can see >> what kind of repeatability / results from the all_cpus trace shows. > >/me is puzzled. > >so all the CPU-loop delays within the -RT kernel are below 250 usecs? I >guess i dont understand what this means then: There were no cases where /proc/sys/kernel/preempt_max_latency went over 250 usec in the RT stress test that I did (for the same test, _PK had over 30 such traces). >| The max CPU latencies in RT are worse than PK as well. The values for >| RT range from 3.00 msec to 5.43 msec and on PK range from 1.45 msec to >| 2.24 msec. > >these come from userspace timestamping? So where userspace detects a >delay the kernel tracer doesnt measure any? Yes. That is correct. Very puzzling to me too. --Mark H Johnson