Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263146AbUJ2I3U (ORCPT ); Fri, 29 Oct 2004 04:29:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263149AbUJ2I3U (ORCPT ); Fri, 29 Oct 2004 04:29:20 -0400 Received: from 213-239-205-147.clients.your-server.de ([213.239.205.147]:14503 "EHLO debian.tglx.de") by vger.kernel.org with ESMTP id S263146AbUJ2I3Q (ORCPT ); Fri, 29 Oct 2004 04:29:16 -0400 Subject: Re: [Fwd: Re: [patch] Real-Time Preemption, -RT-2.6.9-mm1-V0.4] From: Thomas Gleixner Reply-To: tglx@linutronix.de To: Ingo Molnar Cc: Paul Davis , LKML , Lee Revell , mark_h_johnson@raytheon.com, Bill Huey , Adam Heath , Florian Schmidt , Michal Schmidt , Fernando Pablo Lopez-Lezcano , Karsten Wiese , jackit-devel In-Reply-To: <20041029080247.GC30400@elte.hu> References: <1099008264.4199.4.camel@krustophenia.net> <200410290057.i9T0v5I8011561@localhost.localdomain> <20041029080247.GC30400@elte.hu> Content-Type: text/plain Organization: linutronix Date: Fri, 29 Oct 2004 10:21:03 +0200 Message-Id: <1099038063.22387.534.camel@thomas> 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: 1126 Lines: 25 On Fri, 2004-10-29 at 10:02 +0200, Ingo Molnar wrote: > there are multiple possibilities of how this ~700 usecs delay occured: > > - the kernel still has a wakeup bug. But this should be detected by the > tracer which measures the time between when the task hits the > runqueue and the task gets to execute on the CPU. Also, if there is a > critical section in the kernel that is 700 usecs long it would be > detected by _another_, independent timing/tracing mechanism that > measures critical sections. The likelyhood of both the scheduler > _and_ two independent kernel-tracers being buggy in the same way is > quite significantly low. (not to mention the user-space amlat tool > which seems to agree with the kernel instrumentation.) > The sound subsystem uses a lot of sleep_on() variants. We know that they are racy. Might this be related ? tglx - 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/