From: Avi Kivity <avi@qumranet.com>
To: dor.laor@qumranet.com
Cc: Amit Shah <amit.shah@qumranet.com>,
kvm-devel@lists.sourceforge.net,
linux-kernel <linux-kernel@vger.kernel.org>,
Avi Kivity <avi@argo.co.il>, Gerd Hoffmann <kraxel@redhat.com>
Subject: Re: [kvm-devel] Guest kernel hangs in smp kvm for older kernelsprior to tsc sync cleanup
Date: Wed, 19 Dec 2007 19:09:48 +0200 [thread overview]
Message-ID: <4769505C.5020309@qumranet.com> (raw)
In-Reply-To: <47694F35.6070401@qumranet.com>
Dor Laor wrote:
>> > >
>> > > vmx (and svm) allow us to add an offset to the physical tsc. We
>> set it
>> > > on startup to -tsc (so that an rdtsc on boot would return 0), and
>> > > massage it on vcpu migration so that guest rdtsc is monotonic.
>> > >
>> > > The net effect is that tsc on a vcpu can experience large forward
>> jumps
>> > > and changes in rate, but no negative jumps.
>> >
>> > Changes in rate does not sound good. It's possibly what's screwing up
>> > my paravirt clock implementation in smp.
>>
>> Do you mean in the case of VM migration, or just starting them on a
>> single
>> host?
>>
> It's the cpu preemption stuff on local host and not VM migration
No, migrating a vcpu to another cpu.
--
error compiling committee.c: too many arguments to function
WARNING: multiple messages have this Message-ID (diff)
From: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
To: dor.laor-atKUWr5tajBWk0Htik3J/w@public.gmane.org
Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org,
linux-kernel
<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Avi Kivity <avi-7k6+44Jx4zn6gbPvEgmw2w@public.gmane.org>,
Gerd Hoffmann <kraxel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Subject: Re: Guest kernel hangs in smp kvm for older kernelsprior to tsc sync cleanup
Date: Wed, 19 Dec 2007 19:09:48 +0200 [thread overview]
Message-ID: <4769505C.5020309@qumranet.com> (raw)
In-Reply-To: <47694F35.6070401-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
Dor Laor wrote:
>> > >
>> > > vmx (and svm) allow us to add an offset to the physical tsc. We
>> set it
>> > > on startup to -tsc (so that an rdtsc on boot would return 0), and
>> > > massage it on vcpu migration so that guest rdtsc is monotonic.
>> > >
>> > > The net effect is that tsc on a vcpu can experience large forward
>> jumps
>> > > and changes in rate, but no negative jumps.
>> >
>> > Changes in rate does not sound good. It's possibly what's screwing up
>> > my paravirt clock implementation in smp.
>>
>> Do you mean in the case of VM migration, or just starting them on a
>> single
>> host?
>>
> It's the cpu preemption stuff on local host and not VM migration
No, migrating a vcpu to another cpu.
--
error compiling committee.c: too many arguments to function
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next prev parent reply other threads:[~2007-12-19 17:10 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-18 17:20 Guest kernel hangs in smp kvm for older kernels prior to tsc sync cleanup Avi Kivity
2007-12-18 17:20 ` Avi Kivity
2007-12-18 22:19 ` Ingo Molnar
2007-12-18 22:19 ` Ingo Molnar
2007-12-19 6:33 ` Avi Kivity
2007-12-19 6:33 ` Avi Kivity
2007-12-19 11:19 ` [kvm-devel] " Avi Kivity
2007-12-19 11:19 ` Avi Kivity
2007-12-19 11:39 ` [kvm-devel] " Avi Kivity
2007-12-19 14:06 ` Ingo Molnar
2007-12-19 14:06 ` Ingo Molnar
2007-12-19 14:27 ` [kvm-devel] " Avi Kivity
2007-12-19 15:32 ` Glauber de Oliveira Costa
2007-12-19 15:32 ` Glauber de Oliveira Costa
2007-12-19 15:41 ` [kvm-devel] " Avi Kivity
2007-12-20 10:34 ` Glauber de Oliveira Costa
2007-12-20 10:34 ` Glauber de Oliveira Costa
2007-12-19 16:55 ` [kvm-devel] " Amit Shah
2007-12-19 16:55 ` Amit Shah
2007-12-19 17:04 ` [kvm-devel] Guest kernel hangs in smp kvm for older kernelsprior " Dor Laor
2007-12-19 17:04 ` Dor Laor
2007-12-19 17:09 ` Avi Kivity [this message]
2007-12-19 17:09 ` Avi Kivity
2007-12-19 14:53 ` [kvm-devel] Guest kernel hangs in smp kvm for older kernels prior " Avi Kivity
2007-12-19 14:53 ` Avi Kivity
2007-12-19 15:09 ` [kvm-devel] " Ingo Molnar
2007-12-19 15:21 ` Avi Kivity
2007-12-19 15:21 ` Avi Kivity
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