From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jan Kiszka <jan.kiszka@web.de>
Subject: Re: [KVM timekeeping 10/35] Fix deep C-state TSC desynchronization
Date: Wed, 15 Sep 2010 20:27:14 +0200
Message-ID: <4C911002.8060807@web.de>
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>
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Cc: Zachary Amsden <zamsden@redhat.com>, kvm@vger.kernel.org,
	Avi Kivity <avi@redhat.com>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	John Stultz <johnstul@us.ibm.com>, linux-kernel@vger.kernel.org
To: Glauber Costa <glommer@redhat.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <20100915123215.GC3688@mothafucka.localdomain>
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List-Id: kvm.vger.kernel.org

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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.
>=20
> even artificially marked unstable ?
>=20

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=
=2E

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 =3D 0;

on resume...

Jan


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