From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Avi Kivity <avi@redhat.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>,
Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
kurt.hackel@oracle.com, the arch/x86 maintainers <x86@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Glauber de Oliveira Costa <gcosta@redhat.com>,
Xen-devel <xen-devel@lists.xensource.com>,
Keir Fraser <keir.fraser@eu.citrix.com>,
Zach Brown <zach.brown@oracle.com>,
Chris Mason <chris.mason@oracle.com>,
Ingo Molnar <mingo@redhat.com>
Subject: Re: [Xen-devel] Re: [PATCH 3/5] x86/pvclock: add vsyscall implementation
Date: Tue, 13 Oct 2009 13:00:18 -0700 [thread overview]
Message-ID: <4AD4DC52.8090508@goop.org> (raw)
In-Reply-To: <4AD420A4.7050508@redhat.com>
On 10/12/09 23:39, Avi Kivity wrote:
> On 10/12/2009 09:13 PM, Jeremy Fitzhardinge wrote:
>> On 10/12/09 11:29, Avi Kivity wrote:
>>
>>> Good catch. Doesn't that invalidate rdtscp based vgettimeofday on
>>> non-virt as well (assuming p == cpu)?
>>>
>> The tsc clocksource assumes the tsc is (mostly?) synced; it doesn't use
>> rdtscp or make any attempt at per-cpu corrections.
>>
>
> So it's broken or disabled when that assumption is wrong? We could
> easily fix that now. Might even reuse the pvclock structures.
Well, the kernel internally makes more or less the same assumption; the
vsyscall clocksource is the same as the kernel's internal one. I think
idea is that it just drops back to something like hpet if the tsc
doesn't have very simple SMP characteristics.
If the kernel could characterize the per-cpu properties of the tsc more
accurately, then it could use the pvclock mechanism on native.
J
WARNING: multiple messages have this Message-ID (diff)
From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Avi Kivity <avi@redhat.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>,
Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
kurt.hackel@oracle.com, the arch/x86 maintainers <x86@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Glauber de Oliveira Costa <gcosta@redhat.com>,
Xen-devel <xen-devel@lists.xensource.com>,
Keir Fraser <keir.fraser@eu.citrix.com>,
Zach Brown <zach.brown@oracle.com>,
Ingo Molnar <mingo@redhat.com>,
Chris Mason <chris.mason@oracle.com>
Subject: Re: Re: [PATCH 3/5] x86/pvclock: add vsyscall implementation
Date: Tue, 13 Oct 2009 13:00:18 -0700 [thread overview]
Message-ID: <4AD4DC52.8090508@goop.org> (raw)
In-Reply-To: <4AD420A4.7050508@redhat.com>
On 10/12/09 23:39, Avi Kivity wrote:
> On 10/12/2009 09:13 PM, Jeremy Fitzhardinge wrote:
>> On 10/12/09 11:29, Avi Kivity wrote:
>>
>>> Good catch. Doesn't that invalidate rdtscp based vgettimeofday on
>>> non-virt as well (assuming p == cpu)?
>>>
>> The tsc clocksource assumes the tsc is (mostly?) synced; it doesn't use
>> rdtscp or make any attempt at per-cpu corrections.
>>
>
> So it's broken or disabled when that assumption is wrong? We could
> easily fix that now. Might even reuse the pvclock structures.
Well, the kernel internally makes more or less the same assumption; the
vsyscall clocksource is the same as the kernel's internal one. I think
idea is that it just drops back to something like hpet if the tsc
doesn't have very simple SMP characteristics.
If the kernel could characterize the per-cpu properties of the tsc more
accurately, then it could use the pvclock mechanism on native.
J
next prev parent reply other threads:[~2009-10-13 20:00 UTC|newest]
Thread overview: 119+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-06 0:50 [PATCH RFC] Extending pvclock down to usermode for vsyscall Jeremy Fitzhardinge
2009-10-06 0:50 ` Jeremy Fitzhardinge
2009-10-06 0:50 ` [PATCH 1/5] x86/pvclock: make sure rdtsc doesn't speculate out of region Jeremy Fitzhardinge
2009-10-06 0:50 ` Jeremy Fitzhardinge
2009-10-06 0:50 ` [PATCH 2/5] x86/pvclock: no need to use strong read barriers in pvclock_get_time_values Jeremy Fitzhardinge
2009-10-06 0:50 ` Jeremy Fitzhardinge
2009-10-06 0:50 ` [PATCH 3/5] x86/pvclock: add vsyscall implementation Jeremy Fitzhardinge
2009-10-06 0:50 ` Jeremy Fitzhardinge
2009-10-06 9:04 ` Avi Kivity
2009-10-06 9:04 ` Avi Kivity
2009-10-06 14:19 ` Dan Magenheimer
2009-10-06 14:19 ` Dan Magenheimer
2009-10-06 15:11 ` Avi Kivity
2009-10-06 15:11 ` Avi Kivity
2009-10-06 18:46 ` [Xen-devel] " Jeremy Fitzhardinge
2009-10-06 18:46 ` Jeremy Fitzhardinge
2009-10-07 10:25 ` [Xen-devel] " Avi Kivity
2009-10-07 10:25 ` Avi Kivity
2009-10-07 19:29 ` [Xen-devel] " Jeremy Fitzhardinge
2009-10-07 19:29 ` Jeremy Fitzhardinge
2009-10-07 20:09 ` [Xen-devel] " Avi Kivity
2009-10-07 20:09 ` Avi Kivity
2009-10-07 21:19 ` [Xen-devel] " Jeremy Fitzhardinge
2009-10-07 21:19 ` Jeremy Fitzhardinge
2009-10-07 21:37 ` [Xen-devel] " Avi Kivity
2009-10-07 21:37 ` Avi Kivity
2009-10-07 21:51 ` [Xen-devel] " Jeremy Fitzhardinge
2009-10-07 21:51 ` Jeremy Fitzhardinge
2009-10-07 21:53 ` [Xen-devel] " Avi Kivity
2009-10-07 21:53 ` Avi Kivity
2009-10-07 20:48 ` [Xen-devel] " Dan Magenheimer
2009-10-07 20:48 ` Dan Magenheimer
2009-10-07 21:08 ` [Xen-devel] " Avi Kivity
2009-10-07 21:08 ` Avi Kivity
2009-10-07 22:36 ` [Xen-devel] " Dan Magenheimer
2009-10-07 22:36 ` Dan Magenheimer
2009-10-10 0:24 ` [Xen-devel] " Jeremy Fitzhardinge
2009-10-10 0:24 ` Jeremy Fitzhardinge
2009-10-10 18:10 ` [Xen-devel] " Avi Kivity
2009-10-10 18:10 ` Avi Kivity
2009-10-12 18:20 ` [Xen-devel] " Jeremy Fitzhardinge
2009-10-12 18:20 ` Jeremy Fitzhardinge
2009-10-12 18:29 ` [Xen-devel] " Avi Kivity
2009-10-12 18:29 ` Avi Kivity
2009-10-12 19:13 ` [Xen-devel] " Jeremy Fitzhardinge
2009-10-12 19:13 ` Jeremy Fitzhardinge
2009-10-13 6:39 ` [Xen-devel] " Avi Kivity
2009-10-13 6:39 ` Avi Kivity
2009-10-13 20:00 ` Jeremy Fitzhardinge [this message]
2009-10-13 20:00 ` Jeremy Fitzhardinge
2009-10-14 12:32 ` [Xen-devel] " Avi Kivity
2009-10-14 12:32 ` Avi Kivity
2009-10-15 19:17 ` [Xen-devel] " Jeremy Fitzhardinge
2009-10-15 19:17 ` Jeremy Fitzhardinge
2009-10-27 17:29 ` [Xen-devel] " Dan Magenheimer
2009-10-27 17:29 ` Dan Magenheimer
2009-10-27 18:20 ` [Xen-devel] " Jeremy Fitzhardinge
2009-10-27 18:20 ` Jeremy Fitzhardinge
2009-10-28 5:52 ` [Xen-devel] " Avi Kivity
2009-10-28 5:52 ` Avi Kivity
2009-10-28 9:29 ` [Xen-devel] " Glauber Costa
2009-10-28 9:34 ` Avi Kivity
2009-10-28 9:34 ` Avi Kivity
2009-10-28 17:47 ` [Xen-devel] " Jeremy Fitzhardinge
2009-10-28 17:47 ` Jeremy Fitzhardinge
2009-10-29 12:13 ` [Xen-devel] " Avi Kivity
2009-10-29 12:13 ` Avi Kivity
2009-10-29 13:03 ` [Xen-devel] " Chris Mason
2009-10-29 13:03 ` Chris Mason
2009-10-29 14:46 ` [Xen-devel] " Dan Magenheimer
2009-10-29 14:46 ` Dan Magenheimer
2009-10-29 15:07 ` [Xen-devel] " Avi Kivity
2009-10-29 15:07 ` Avi Kivity
2009-10-29 15:55 ` [Xen-devel] " Dan Magenheimer
2009-10-29 15:55 ` Dan Magenheimer
2009-10-29 16:15 ` [Xen-devel] " Dan Magenheimer
2009-10-29 16:15 ` Dan Magenheimer
2009-11-01 9:28 ` [Xen-devel] " Avi Kivity
2009-11-01 9:28 ` Avi Kivity
2009-11-02 15:28 ` [Xen-devel] " Dan Magenheimer
2009-11-02 15:28 ` Dan Magenheimer
2009-11-02 15:41 ` [Xen-devel] " Avi Kivity
2009-11-02 15:41 ` Avi Kivity
2009-11-01 9:32 ` [Xen-devel] " Avi Kivity
2009-11-01 9:32 ` Avi Kivity
2009-11-02 15:46 ` [Xen-devel] " Dan Magenheimer
2009-11-02 15:46 ` Dan Magenheimer
2009-11-03 5:12 ` [Xen-devel] " Avi Kivity
2009-11-03 5:12 ` Avi Kivity
2009-11-04 20:30 ` [Xen-devel] " Dan Magenheimer
2009-11-04 20:30 ` Dan Magenheimer
2009-11-05 6:47 ` [Xen-devel] " Avi Kivity
2009-11-05 6:47 ` Avi Kivity
2009-11-05 14:52 ` [Xen-devel] " Dan Magenheimer
2009-11-05 14:52 ` Dan Magenheimer
2009-11-05 15:07 ` [Xen-devel] " Keir Fraser
2009-11-05 15:07 ` Keir Fraser
2009-11-04 21:19 ` [Xen-devel] " john stultz
2009-11-04 21:19 ` john stultz
2009-11-04 21:28 ` Dan Magenheimer
2009-11-04 21:28 ` Dan Magenheimer
2009-11-05 0:02 ` [Xen-devel] " john stultz
2009-11-05 0:02 ` john stultz
2009-11-05 0:45 ` [Xen-devel] " Dan Magenheimer
2009-11-05 0:45 ` Dan Magenheimer
2009-10-30 23:30 ` pvclock implementation in pv_ops kernel: why not __native_read_tsc()? Dan Magenheimer
2009-10-31 1:17 ` Jeremy Fitzhardinge
2009-10-06 0:50 ` [PATCH 4/5] x86/fixmap: add a predicate for usermode fixmaps Jeremy Fitzhardinge
2009-10-06 0:50 ` Jeremy Fitzhardinge
2009-10-06 10:23 ` [Xen-devel] " Jan Beulich
2009-10-06 10:23 ` Jan Beulich
2009-10-06 18:47 ` [Xen-devel] " Jeremy Fitzhardinge
2009-10-06 18:47 ` Jeremy Fitzhardinge
2009-10-06 0:50 ` [PATCH 5/5] xen/time: add pvclock_clocksource_vread support Jeremy Fitzhardinge
2009-10-06 0:50 ` Jeremy Fitzhardinge
2009-10-06 10:28 ` [Xen-devel] " Jan Beulich
2009-10-06 10:28 ` Jan Beulich
2009-10-06 18:48 ` [Xen-devel] " Jeremy Fitzhardinge
2009-10-06 18:48 ` Jeremy Fitzhardinge
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