From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764735AbXGYH4s (ORCPT ); Wed, 25 Jul 2007 03:56:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759502AbXGYH4k (ORCPT ); Wed, 25 Jul 2007 03:56:40 -0400 Received: from an-out-0708.google.com ([209.85.132.241]:10443 "EHLO an-out-0708.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751966AbXGYH4j (ORCPT ); Wed, 25 Jul 2007 03:56:39 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=VguncO/iUvYpD+faFF4H7baZlVH/bSfqcqpX0PuOnWWpElKgOYurYyXl3xOm7HEG4xKg11WKjl+g/Q3VPsED2PcRaR+bbEnDh4wjgiQ66tUpYF6b3/ZMaqGkBHZUYhTlio2Lnj92ew70gVzBKEL61AfVGN3IcEm555aZfaVraDE= Message-ID: Date: Wed, 25 Jul 2007 09:56:38 +0200 From: "Henri Hunnekens" To: "Ingo Molnar" Subject: Re: TSC calibration sometimes not correct with RT patch. Cc: linux-kernel , "Thomas Gleixner" In-Reply-To: <20070725073949.GB595@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20070725073949.GB595@elte.hu> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Some more information, the problems occurs on a SMP machine. I've added the system logging which displays the CPU speed. The last line shows an inaccurate processor speed! I'll try an update, but I expect this has something to do with the TSC calibration and that hasn't changed, If I'm correct. Jul 23 07:50:53 localhost kernel: Detected 1795.663 MHz processor. Jul 23 08:07:35 localhost kernel: Detected 1795.707 MHz processor. Jul 23 08:27:44 localhost kernel: Detected 1795.623 MHz processor. Jul 23 08:36:56 localhost kernel: Detected 1795.599 MHz processor. Jul 23 08:43:36 localhost kernel: Detected 1795.641 MHz processor. Jul 23 08:55:12 localhost kernel: Detected 1795.587 MHz processor. Jul 23 09:13:26 localhost kernel: Detected 1795.625 MHz processor. Jul 23 09:38:31 localhost kernel: Detected 1795.573 MHz processor. Jul 23 09:54:39 localhost kernel: Detected 1795.662 MHz processor. Jul 23 10:01:57 localhost kernel: Detected 1795.645 MHz processor. Jul 23 10:22:18 localhost kernel: Detected 1795.648 MHz processor. Jul 23 10:55:43 localhost kernel: Detected 1795.582 MHz processor. Jul 23 11:00:29 localhost kernel: Detected 1795.589 MHz processor. Jul 23 11:08:32 localhost kernel: Detected 1795.632 MHz processor. Jul 23 11:24:30 localhost kernel: Detected 1795.610 MHz processor. Jul 23 13:40:28 localhost kernel: Detected 1795.607 MHz processor. Jul 23 13:47:15 localhost kernel: Detected 1795.557 MHz processor. Jul 23 13:51:40 localhost kernel: Detected 1795.641 MHz processor. Jul 23 14:20:38 localhost kernel: Detected 1795.646 MHz processor. Jul 23 14:41:08 localhost kernel: Detected 1795.615 MHz processor. Jul 23 14:49:27 localhost kernel: Detected 1795.677 MHz processor. Jul 23 14:56:51 localhost kernel: Detected 1795.596 MHz processor. Jul 24 07:44:17 localhost kernel: Detected 1795.651 MHz processor. Jul 24 07:51:07 localhost kernel: Detected 1795.585 MHz processor. Jul 24 09:05:18 localhost kernel: Detected 1795.660 MHz processor. Jul 24 10:32:21 localhost kernel: Detected 1795.614 MHz processor. Jul 24 10:42:39 localhost kernel: Detected 1823.703 MHz processor. <-------------- 2007/7/25, Ingo Molnar : > > * Henri Hunnekens wrote: > > > I've seen that the calbration of the TSC timer was not always done > > correctly, which resulted in incorrect timers. > > > > I found out that local_irq_disable is used before the calibration is > > started. However with the RT patch applied this does not mean that the > > interrupts are disabled and therefore the calibration may fails when > > it's interrupted by an interrupt. Correct me if I'm wrong. > > local_irq_disable() still disables interrupts, even in PREEMPT_RT. So > the problem should be elsewhere. Can you see similar problems on .22-rt > too? The hrt code saw a number of updates there. > > Ingo >