From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zachary Amsden Subject: Re: [KVM timekeeping 10/35] Fix deep C-state TSC desynchronization Date: Fri, 17 Sep 2010 12:09:56 -1000 Message-ID: <4C93E734.4040208@redhat.com> References: <1282291669-25709-1-git-send-email-zamsden@redhat.com> <1282291669-25709-11-git-send-email-zamsden@redhat.com> <4C8F3C03.50306@siemens.com> <4C904685.9090402@redhat.com> <4C907F3D.6070709@web.de> <20100915123215.GC3688@mothafucka.localdomain> <4C911002.8060807@web.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Glauber Costa , kvm@vger.kernel.org, Avi Kivity , Marcelo Tosatti , Thomas Gleixner , John Stultz , linux-kernel@vger.kernel.org To: Jan Kiszka Return-path: Received: from mx1.redhat.com ([209.132.183.28]:33404 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752125Ab0IQWKO (ORCPT ); Fri, 17 Sep 2010 18:10:14 -0400 In-Reply-To: <4C911002.8060807@web.de> Sender: kvm-owner@vger.kernel.org List-ID: On 09/15/2010 08:27 AM, Jan Kiszka wrote: > Am 15.09.2010 14:32, Glauber Costa wrote: > >> On Wed, Sep 15, 2010 at 10:09:33AM +0200, Jan Kiszka wrote: >> >>>> In any case, I'll proceed with the forcing of unstable TSC and HPET >>>> clocksource and see what happens. >>>> >>> I tried that before, but it did not trigger the issue that kvm-clock >>> guests no longer boot properly. This only happens if the TSC is marked >>> unstable. >>> >> even artificially marked unstable ? >> >> > Yes. As soon as I hack tsc_unstable to 1, things go wrong. When I hack > it back to 0, guest that wants kvm-clock boots again and seem to run fine. > > This is issue #2, I guess. Issue #2 remains that the TSC is marked > unstable. I have the feeling that this is bogus, maybe due to lacking > suspend/resume awareness? The tsc clocksource does > > clocksource_tsc.cycle_last = 0; > > on resume... > > Jan > > I have now reproduced this exactly. Shouldn't be long before I have a solution. Zach