Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267591AbUJOLnQ (ORCPT ); Fri, 15 Oct 2004 07:43:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267679AbUJOLnQ (ORCPT ); Fri, 15 Oct 2004 07:43:16 -0400 Received: from mx1.elte.hu ([157.181.1.137]:22934 "EHLO mx1.elte.hu") by vger.kernel.org with ESMTP id S267591AbUJOLnO (ORCPT ); Fri, 15 Oct 2004 07:43:14 -0400 Date: Fri, 15 Oct 2004 13:44:05 +0200 From: Ingo Molnar To: Florian Schmidt Cc: linux-kernel@vger.kernel.org, Lee Revell , Rui Nuno Capela , Mark_H_Johnson@Raytheon.com, "K.R. Foley" , Daniel Walker , Bill Huey , Andrew Morton , Adam Heath , Lorenzo Allegrucci , Dipankar Sarma Subject: Re: [patch] Real-Time Preemption, -VP-2.6.9-rc4-mm1-U1 Message-ID: <20041015114405.GA22823@elte.hu> References: <20041011215909.GA20686@elte.hu> <20041012091501.GA18562@elte.hu> <20041012123318.GA2102@elte.hu> <20041012195424.GA3961@elte.hu> <20041013061518.GA1083@elte.hu> <20041014002433.GA19399@elte.hu> <20041014143131.GA20258@elte.hu> <20041015132236.6b8bd16e@mango.fruits.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20041015132236.6b8bd16e@mango.fruits.de> User-Agent: Mutt/1.4.1i X-ELTE-SpamVersion: MailScanner 4.31.6-itk1 (ELTE 1.2) SpamAssassin 2.63 ClamAV 0.73 X-ELTE-VirusStatus: clean X-ELTE-SpamCheck: no X-ELTE-SpamCheck-Details: score=-4.9, required 5.9, autolearn=not spam, BAYES_00 -4.90 X-ELTE-SpamLevel: X-ELTE-SpamScore: -4 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1698 Lines: 49 * Florian Schmidt wrote: > > i have released the -U1 PREEMPT_REALTIME patch: > > > > http://redhat.com/~mingo/voluntary-preempt/voluntary-preempt-2.6.9-rc4-mm1-U1 > > Ok, > > with the help of Paul Davis i think i have found what's causing the jackd > FP exception. It seems to be a bug in the kernel when PREEMPT_REALTIME is > enabled: > > ~$ cat /proc/cpuinfo|grep cpu > cpu family : 6 > cpu MHz : 0.001 > cpuid level : 1 > > Mhz == 0.001? Hrmm. No wonder jackd was freaking out in its timing code.. > The real cpu speed is 1.2ghz. > > flo > > P.S.: Will retry with U3, to see if this persists. ah ... good eyes. Seems to be working fine here: saturn:~> cat /proc/cpuinfo | grep -i mhz cpu MHz : 2051.126 saturn:~> uname -a Linux saturn 2.6.9-rc4-mm1-VP-U4 #288 SMP Fri Oct 15 12:31:38 CEST 2004 but it could easily be happening on some CPUs only. Let me know if that problem persists. Fortunately i think it will be at most a detection problem, not some FPU breakage that i initially suspected. it could be the following thing: if you got an smp_processor_id() warning _in the CPU detection code_ in earlier PREEMPT_REALTIME kernels then the kernel could easily see that the CPU is extremely slow, because it didnt manage to do much work (due to the long printout...). So i'd say if this happens again it's most likely a debug printout in the 'calibrating delay loop' phase. Ingo - 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/