Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760911AbXJDTSw (ORCPT ); Thu, 4 Oct 2007 15:18:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755713AbXJDTSo (ORCPT ); Thu, 4 Oct 2007 15:18:44 -0400 Received: from ug-out-1314.google.com ([66.249.92.172]:17612 "EHLO ug-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755119AbXJDTSn (ORCPT ); Thu, 4 Oct 2007 15:18:43 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:date:from:to:cc:subject:message-id:references:mime-version:content-type:content-disposition:content-transfer-encoding:in-reply-to:user-agent; b=d7Z6uxMZO856JcEKBzaO5V4FHHa0HhZI1c0sxcJTkaxPoizXNuRropIYqOlmFYCkFTr7PARZ6IR0FQFW4IJMr8bwYe07P5ZJtocbs0BBDLCR8lt7vWtNr9b79dfqgj2H+GanMM+UL47LVk7fY4akaSIjrOCeOnaE/sZjfmwOYJ4= Date: Thu, 4 Oct 2007 21:19:21 +0200 From: Luca Tettamanti To: Frans Pop Cc: Willy Tarreau , LKML , Ilpo =?iso-8859-1?Q?J=E4rvinen?= , "Alexander E. Patrakov" Subject: Re: Decreasing stime running confuses top (was: top displaying 9999% CPU usage) Message-ID: <20071004191921.GA24011@dreamland.darkstar.lan> References: <200710031433.34504.elendil@planet.nl> <200710032127.42147.elendil@planet.nl> <20071003202446.GQ10199@1wt.eu> <200710040132.45062.elendil@planet.nl> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <200710040132.45062.elendil@planet.nl> User-Agent: Mutt/1.5.16 (2007-06-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1877 Lines: 46 Il Thu, Oct 04, 2007 at 01:32:44AM +0200, Frans Pop ha scritto: > On Wednesday 03 October 2007, you wrote: > > On Wed, Oct 03, 2007 at 09:27:41PM +0200, Frans Pop wrote: > > > On Wednesday 03 October 2007, you wrote: > > > > On Wed, 3 Oct 2007, Ilpo J?rvinen wrote: > > > > > On Wed, 3 Oct 2007, Frans Pop wrote: > > > > > > The only change is in 2 consecutive columns: "2911 502" -> "2912 > > > > > > 500". Is processor usage calculated from those? Can someone > > > > > > explain how? > > > > > > > > > > The latter seems to be utime ...decreasing. No wonder if > > > > > arithmetics will give strange results (probably top is using > > > > > unsigned delta?)... > > > > > > > > Hmm, minor miscounting from my side, stime seems more appropriate... > > > > > > So, is it normal that stime decreases sometimes or a kernel bug? > > > /me expects the last... > > > > Let me guess... Dual core AMD64 ? > > Nope: Intel(R) Pentium(R) D CPU 3.20GHz I just notice the same thing here, with a Core2 Duo (which is supposed to have synced TSCs) and working HPET. > The following may well be relevant. > With 2.6.22 and early 2.6.23-rc kernels (rc3-rc6) I often had this in my > kernel log (see http://lkml.org/lkml/2007/9/16/45): > checking TSC synchronization [CPU#0 -> CPU#1]: > Measured 248 cycles TSC warp between CPUs, turning off TSC clock. > Marking TSC unstable due to check_tsc_sync_source failed I don't see this though, TSCs are always syncronized between the 2 cores. Luca -- Ligabue canta: "Tutti vogliono viaggiare in primaaaa..." Io ci ho provato e dopo un chilometro ho fuso il motore e bruciato la frizione... - 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/