From: Peter Zijlstra <peterz@infradead.org>
To: Avi Kivity <avi@redhat.com>
Cc: Glauber Costa <glommer@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Jeremy Fitzhardinge <jeremy@goop.org>,
Marcelo Tosatti <mtosatti@redhat.com>,
Zachary Amsden <zamsden@redhat.com>
Subject: Re: [PATCH 1/5] Add a global synchronization point for pvclock
Date: Mon, 19 Apr 2010 12:59:05 +0200 [thread overview]
Message-ID: <1271674745.1674.802.camel@laptop> (raw)
In-Reply-To: <4BCC3617.6050106@redhat.com>
On Mon, 2010-04-19 at 13:53 +0300, Avi Kivity wrote:
> On 04/19/2010 01:49 PM, Peter Zijlstra wrote:
> >
> >> Right, so on x86 we have:
> >>
> >> X86_FEATURE_CONSTANT_TSC, which only states that TSC is frequency
> >> independent, not that it doesn't stop in C states and similar fun stuff.
> >>
> >> X86_FEATURE_TSC_RELIABLE, which IIRC should indicate the TSC is constant
> >> and synced between cores.
> >>
> > Fun, we also have:
> >
> > X86_FEATURE_NONSTOP_TSC, which states the thing doesn't stop in C
> > states.
> >
>
> All of them? I though tsc stops in some mwait deep REM sleep thing.
The idea is that TSC will not stop ever (except s2r like stuff), not
sure about the actual implementation of the NONSTOP_TSC bit though.
> So what do we need? test for both TSC_RELIABLE and NONSTOP_TSC? IMO
> TSC_RELIABLE should imply NONSTOP_TSC.
Yeah, I think RELIABLE does imply NONSTOP and CONSTANT, but NONSTOP &&
CONSTANT does not make RELIABLE.
next prev parent reply other threads:[~2010-04-19 10:59 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-15 18:37 [PATCH 0/5] pv clock misc fixes Glauber Costa
2010-04-15 18:37 ` [PATCH 1/5] Add a global synchronization point for pvclock Glauber Costa
2010-04-15 18:37 ` [PATCH 2/5] change msr numbers for kvmclock Glauber Costa
2010-04-15 18:37 ` [PATCH 3/5] Try using new kvm clock msrs Glauber Costa
2010-04-15 18:37 ` [PATCH 4/5] export new cpuid KVM_CAP Glauber Costa
2010-04-15 18:37 ` [PATCH 5/5] add documentation about kvmclock Glauber Costa
2010-04-15 19:28 ` Randy Dunlap
2010-04-15 20:10 ` Glauber Costa
2010-04-17 18:58 ` [PATCH 4/5] export new cpuid KVM_CAP Avi Kivity
2010-04-19 14:50 ` Glauber Costa
2010-04-20 9:29 ` Avi Kivity
2010-04-17 18:55 ` [PATCH 3/5] Try using new kvm clock msrs Avi Kivity
2010-04-17 18:51 ` [PATCH 2/5] change msr numbers for kvmclock Avi Kivity
2010-04-16 20:23 ` [PATCH 1/5] Add a global synchronization point for pvclock Marcelo Tosatti
2010-04-16 20:36 ` Jeremy Fitzhardinge
2010-04-16 21:05 ` Zachary Amsden
2010-04-19 10:39 ` Peter Zijlstra
2010-04-19 10:50 ` Avi Kivity
2010-04-19 11:05 ` Peter Zijlstra
2010-04-19 11:10 ` Avi Kivity
2010-04-19 14:21 ` Glauber Costa
2010-04-19 14:33 ` Avi Kivity
2010-04-19 14:46 ` Peter Zijlstra
2010-04-19 16:18 ` Jeremy Fitzhardinge
2010-04-20 9:31 ` Avi Kivity
2010-04-20 18:23 ` Jeremy Fitzhardinge
2010-04-20 18:54 ` Avi Kivity
2010-04-20 19:42 ` Jeremy Fitzhardinge
2010-04-21 0:07 ` Zachary Amsden
2010-04-22 13:11 ` Glauber Costa
2010-04-23 1:44 ` Zachary Amsden
2010-04-23 9:34 ` Avi Kivity
2010-04-23 19:22 ` Jeremy Fitzhardinge
2010-04-23 19:25 ` Avi Kivity
2010-04-23 21:31 ` Zachary Amsden
2010-04-23 21:35 ` Jeremy Fitzhardinge
2010-04-23 21:41 ` Zachary Amsden
2010-04-24 9:30 ` Avi Kivity
2010-04-24 9:29 ` Avi Kivity
2010-04-19 16:11 ` Jeremy Fitzhardinge
2010-04-19 14:26 ` Glauber Costa
2010-04-19 16:19 ` Jeremy Fitzhardinge
2010-04-19 18:25 ` Glauber Costa
2010-04-20 1:57 ` Marcelo Tosatti
2010-04-20 9:35 ` Avi Kivity
2010-04-20 12:59 ` Glauber Costa
2010-04-20 15:16 ` Avi Kivity
2010-04-21 0:01 ` Zachary Amsden
2010-04-21 8:06 ` Avi Kivity
2010-04-17 18:48 ` Avi Kivity
2010-04-17 18:49 ` Avi Kivity
2010-04-19 10:43 ` Peter Zijlstra
2010-04-19 10:47 ` Avi Kivity
2010-04-19 10:56 ` Peter Zijlstra
2010-04-19 11:13 ` Avi Kivity
2010-04-19 11:19 ` Peter Zijlstra
2010-04-19 11:40 ` Avi Kivity
2010-04-19 14:32 ` Glauber Costa
2010-04-19 14:37 ` Avi Kivity
2010-04-19 10:46 ` Peter Zijlstra
2010-04-19 10:49 ` Avi Kivity
2010-04-19 10:51 ` Peter Zijlstra
2010-04-19 10:54 ` Avi Kivity
2010-04-19 18:35 ` Zachary Amsden
2010-04-20 9:39 ` Avi Kivity
2010-04-21 0:05 ` Zachary Amsden
2010-04-21 8:08 ` Avi Kivity
2010-04-19 10:49 ` Peter Zijlstra
2010-04-19 10:53 ` Avi Kivity
2010-04-19 10:59 ` Peter Zijlstra [this message]
2010-04-19 11:35 ` Avi Kivity
2010-10-25 23:30 ` Jeremy Fitzhardinge
2010-10-26 8:14 ` Avi Kivity
2010-10-26 10:49 ` Glauber Costa
2010-10-26 17:04 ` Jeremy Fitzhardinge
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