From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757094Ab0E1Ad4 (ORCPT ); Thu, 27 May 2010 20:33:56 -0400 Received: from mail.svr02.mucip.net ([83.170.6.69]:48752 "EHLO mailout.mucip.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756676Ab0E1AdI (ORCPT ); Thu, 27 May 2010 20:33:08 -0400 X-Submitted: to mailout.mucip.net (Postfix) with ESMTPSA id E95CD496A Message-ID: <4BFF0F3F.9050800@birkenwald.de> Date: Fri, 28 May 2010 02:33:03 +0200 From: Bernhard Schmidt User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.9) Gecko/20100423 Lightning/1.0b1 Thunderbird/3.0.4 MIME-Version: 1.0 To: john stultz CC: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Thomas Gleixner , Ingo Molnar Subject: Re: Clock jumps References: <20100525062100.GP22163@redhat.com> <4BFD5616.6070302@cora.nwra.com> <4D7E210A-4694-4B6E-B721-6024CE96ABC0@suse.de> <4BFEE8A2.30706@birkenwald.de> <1275004816.1813.15.camel@work-vm> In-Reply-To: <1275004816.1813.15.camel@work-vm> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 28.05.2010 02:00, john stultz wrote: Hi John, > Looking at the diff: > --- dmesg-lenny 2010-05-27 16:45:33.000000000 -0700 > +++ dmesg-squeeze 2010-05-27 16:46:14.000000000 -0700 > @@ -132,8 +132,8 @@ > console [ttyS1] enabled > hpet clockevent registered > Fast TSC calibration using PIT > -Detected 2660.398 MHz processor. > -Calibrating delay loop (skipped), value calculated using timer frequency.. 5320.79 BogoMIPS (lpj=10641592) > +Detected 2613.324 MHz processor. > +Calibrating delay loop (skipped), value calculated using timer frequency.. 5226.64 BogoMIPS (lpj=10453296) > Security Framework initialized > Dentry cache hash table entries: 524288 (order: 10, 4194304 bytes) > Inode-cache hash table entries: 262144 (order: 9, 2097152 bytes) > @@ -160,7 +160,7 @@ > CPU0: Intel(R) Xeon(R) CPU 3075 @ 2.66GHz stepping 0b > Booting Node 0, Processors #1 > Brought up 2 CPUs > -Total of 2 processors activated (10640.79 BogoMIPS). > +Total of 2 processors activated (10546.63 BogoMIPS). > NET: Registered protocol family 16 > ACPI: bus type pci registered > PCI: MMCONFIG for domain 0000 [bus 00-ff] at [mem 0xe0000000-0xefffffff] (base 0xe0000000) > > So you can see in the above the during the second boot the TSC > calibration was badly mis-calculated. This was the cause of the skew. > > Not sure how that might be linked to the distro upgrade. It could have > been something like SMI damage during the calibration time, but I > thought the calibration loop watched for that. > > Bernhard: I expect with all those vms, this machine isn't rebooted > frequently. So could you look at the logs to see how much the "Detected > xxxx.yyy MHz processor." line varies by across a few other boots (if > they still exist?). Correct, the box isn't rebooted often, but I do have a few dmesg outputs laying around. lpj was always almost the same until the very last boot which screwed up the clock. dmesg:[ 0.000000] Linux version 2.6.33 (root@svr02) (gcc version 4.3.2 (Debian 4.3.2-1.1) ) #1 SMP Sun Mar 7 23:01:45 CET 2010 dmesg:[ 0.008005] Calibrating delay loop (skipped), value calculated using timer frequency.. 5226.64 BogoMIPS (lpj=10453296) dmesg:[ 0.288002] Total of 2 processors activated (10546.63 BogoMIPS). dmesg.0:[ 0.000000] Linux version 2.6.33 (root@svr02) (gcc version 4.3.2 (Debian 4.3.2-1.1) ) #1 SMP Sun Mar 7 23:01:45 CET 2010 dmesg.0:[ 0.008005] Calibrating delay loop (skipped), value calculated using timer frequency.. 5320.79 BogoMIPS (lpj=10641592) dmesg.0:[ 0.274022] Total of 2 processors activated (10640.79 BogoMIPS). dmesg.1.gz:[ 0.000000] Linux version 2.6.32-rc7 (root@svr02) (gcc version 4.3.2 (Debian 4.3.2-1.1) ) #1 SMP Thu Nov 19 14:36:03 CET 2009 dmesg.1.gz:[ 0.012004] Calibrating delay loop (skipped), value calculated using timer frequency.. 5319.06 BogoMIPS (lpj=10638120) dmesg.1.gz:[ 0.016000] Calibrating delay using timer specific routine.. 5319.99 BogoMIPS (lpj=10639980) dmesg.1.gz:[ 0.260003] Total of 2 processors activated (10639.05 BogoMIPS). dmesg.2.gz:[ 0.000000] Linux version 2.6.32-rc7 (root@svr02) (gcc version 4.3.2 (Debian 4.3.2-1.1) ) #1 SMP Thu Nov 19 14:36:03 CET 2009 dmesg.2.gz:[ 0.012005] Calibrating delay loop (skipped), value calculated using timer frequency.. 5319.35 BogoMIPS (lpj=10638712) dmesg.2.gz:[ 0.016000] Calibrating delay using timer specific routine.. 5319.99 BogoMIPS (lpj=10639990) dmesg.2.gz:[ 0.261567] Total of 2 processors activated (10639.35 BogoMIPS). dmesg.3.gz:[ 0.000000] Linux version 2.6.32-rc7 (root@svr02) (gcc version 4.3.2 (Debian 4.3.2-1.1) ) #1 SMP Thu Nov 19 14:36:03 CET 2009 dmesg.3.gz:[ 0.012005] Calibrating delay loop (skipped), value calculated using timer frequency.. 5319.97 BogoMIPS (lpj=10639956) dmesg.3.gz:[ 0.016000] Calibrating delay using timer specific routine.. 5319.99 BogoMIPS (lpj=10639987) dmesg.3.gz:[ 0.257152] Total of 2 processors activated (10639.97 BogoMIPS). dmesg.4.gz:[ 0.000000] Linux version 2.6.32-rc7 (root@svr02) (gcc version 4.3.2 (Debian 4.3.2-1.1) ) #1 SMP Thu Nov 19 14:36:03 CET 2009 dmesg.4.gz:[ 0.012005] Calibrating delay loop (skipped), value calculated using timer frequency.. 5319.84 BogoMIPS (lpj=10639688) dmesg.4.gz:[ 0.016000] Calibrating delay using timer specific routine.. 5319.99 BogoMIPS (lpj=10639993) dmesg.4.gz:[ 0.253571] Total of 2 processors activated (10639.84 BogoMIPS). If necessary I can reboot once more, but I'd like to avoid it. Bernhard