From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932967Ab0E0WMP (ORCPT ); Thu, 27 May 2010 18:12:15 -0400 Received: from mail.svr02.mucip.net ([83.170.6.69]:56857 "EHLO mailout.mucip.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753285Ab0E0WMN (ORCPT ); Thu, 27 May 2010 18:12:13 -0400 X-Submitted: to mailout.mucip.net (Postfix) with ESMTPSA id 292864969 Message-ID: <4BFEEE3A.1010403@birkenwald.de> Date: Fri, 28 May 2010 00:12:10 +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: Zachary Amsden CC: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: Clock jumps References: <20100525062100.GP22163@redhat.com> <4BFD5616.6070302@cora.nwra.com> <4D7E210A-4694-4B6E-B721-6024CE96ABC0@suse.de> <4BFEE9F3.8040200@redhat.com> In-Reply-To: <4BFEE9F3.8040200@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27.05.2010 23:53, Zachary Amsden wrote: Hello Zachary, > I have server side fixes for this kvm-clock which seem to give me a > stable clock on this machine, but for true SMP stability, you will need > Glauber's guest side changes to kvmclock as well. It is impossible to > guarantee strictly monotonic clocksource across multiple CPUs when > frequency is dynamically changing (and also because of the C1E idle > problems). Is all this relevant only when the host is on TSC? Because I have seen these jumps when the host was on HPET and the guests were using kvm-clock. Anyway, can you send me both patches? I'd like to try it, but I have completely lost track where the up-to-date patches are. Bernhard