Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262024AbUKJRgg (ORCPT ); Wed, 10 Nov 2004 12:36:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262023AbUKJRgf (ORCPT ); Wed, 10 Nov 2004 12:36:35 -0500 Received: from lax-gate3.raytheon.com ([199.46.200.232]:16824 "EHLO lax-gate3.raytheon.com") by vger.kernel.org with ESMTP id S262022AbUKJRgX (ORCPT ); Wed, 10 Nov 2004 12:36:23 -0500 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 , Thomas Gleixner , Michal Schmidt From: Mark_H_Johnson@raytheon.com Subject: Re: [patch] Real-Time Preemption, -RT-2.6.10-rc1-mm3-V0.7.23 Date: Wed, 10 Nov 2004 11:35:18 -0600 Message-ID: X-MIMETrack: Serialize by Router on RTSHOU-DS01/RTS/Raytheon/US(Release 6.5.2|June 01, 2004) at 11/10/2004 11:35:29 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: 1353 Lines: 27 >you have to build another kernel for them. irqs-off and preempt-off >timing can be mixed freely (and both can be enabled in the same kernel), >but wakeup timing deserves its own .config space and since it's not >mixable with the other two methods i didnt see much point in enabling >all 3 at once with strange dependencies between them. Is this a big >issue? Normally i think the wakeup timing is more than enough to get a >feel of latencies, and if something specific is suspected the other ones >can be turned on. Just that it takes an hour or so to rebuild the kernel plus the disk storage to keep two kernels instead of one. The wakeup latencies I am seeing are all quite small, but the overhead I am seeing at the application level have been quite high. Only 40 wakeup latencies > 50 usec in a half hour of testing. I guess I'll build a .24 without wakeup timing to see what kind of problems I'm having. I can send you the wakeup timing traces if you are interested but they are all really short (< 100 usec) or appear to indicate a hardware contention problem (one step at 100 usec or so). --Mark - 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/