From: Avi Kivity <avi@redhat.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
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@oracle.com, chris.mason@oracle.com,
Ingo Molnar <mingo@redhat.com>
Subject: Re: [Xen-devel] Re: [PATCH 3/5] x86/pvclock: add vsyscall implementation
Date: Wed, 28 Oct 2009 07:52:04 +0200 [thread overview]
Message-ID: <4AE7DC04.7080706@redhat.com> (raw)
In-Reply-To: <4AE739DA.20601@goop.org>
On 10/27/2009 08:20 PM, Jeremy Fitzhardinge wrote:
> On 10/27/09 10:29, Dan Magenheimer wrote:
>
>> Is there any way for an application to conclusively determine
>> programmatically if the "fast vsyscall" pvclock is functional
>> vs the much much slower gettimeofday/clock_gettime equivalents?
>>
>> If not, might it be possible to implement some (sysfs?)
>> way to determine this, that would also be backwards compatible
>> to existing OS's that don't have pvclock+vsyscall supported?
>>
>>
> It would probably be simplest and most portable for the app to just
> measure the performance of gettimeofday and see if it meets its needs.
>
How can you reliably measure performance in a virtualized environment?
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
next prev parent reply other threads:[~2009-10-28 5:52 UTC|newest]
Thread overview: 59+ 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 ` [PATCH 1/5] x86/pvclock: make sure rdtsc doesn't speculate out of region 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 ` [PATCH 3/5] x86/pvclock: add vsyscall implementation Jeremy Fitzhardinge
2009-10-06 9:04 ` Avi Kivity
2009-10-06 14:19 ` Dan Magenheimer
2009-10-06 15:11 ` Avi Kivity
2009-10-06 18:46 ` [Xen-devel] " Jeremy Fitzhardinge
2009-10-07 10:25 ` Avi Kivity
2009-10-07 19:29 ` Jeremy Fitzhardinge
2009-10-07 20:09 ` Avi Kivity
2009-10-07 21:19 ` Jeremy Fitzhardinge
2009-10-07 21:37 ` Avi Kivity
2009-10-07 21:51 ` Jeremy Fitzhardinge
2009-10-07 21:53 ` Avi Kivity
2009-10-07 20:48 ` Dan Magenheimer
2009-10-07 21:08 ` Avi Kivity
2009-10-07 22:36 ` Dan Magenheimer
2009-10-10 0:24 ` Jeremy Fitzhardinge
2009-10-10 18:10 ` Avi Kivity
2009-10-12 18:20 ` Jeremy Fitzhardinge
2009-10-12 18:29 ` Avi Kivity
2009-10-12 19:13 ` Jeremy Fitzhardinge
2009-10-13 6:39 ` Avi Kivity
2009-10-13 20:00 ` Jeremy Fitzhardinge
2009-10-14 12:32 ` Avi Kivity
2009-10-15 19:17 ` Jeremy Fitzhardinge
2009-10-27 17:29 ` Dan Magenheimer
2009-10-27 18:20 ` Jeremy Fitzhardinge
2009-10-28 5:52 ` Avi Kivity [this message]
2009-10-28 9:29 ` Glauber Costa
2009-10-28 9:34 ` Avi Kivity
2009-10-28 17:47 ` Jeremy Fitzhardinge
2009-10-29 12:13 ` Avi Kivity
2009-10-29 13:03 ` Chris Mason
2009-10-29 14:46 ` Dan Magenheimer
2009-10-29 15:07 ` Avi Kivity
2009-10-29 15:55 ` Dan Magenheimer
2009-10-29 16:15 ` Dan Magenheimer
2009-11-01 9:28 ` Avi Kivity
2009-11-02 15:28 ` Dan Magenheimer
2009-11-02 15:41 ` Avi Kivity
2009-11-01 9:32 ` Avi Kivity
2009-11-02 15:46 ` Dan Magenheimer
2009-11-03 5:12 ` Avi Kivity
2009-11-04 20:30 ` Dan Magenheimer
2009-11-05 6:47 ` Avi Kivity
2009-11-05 14:52 ` Dan Magenheimer
2009-11-05 15:07 ` Keir Fraser
2009-11-04 21:19 ` john stultz
2009-11-04 21:28 ` Dan Magenheimer
2009-11-05 0:02 ` john stultz
2009-11-05 0:45 ` Dan Magenheimer
2009-10-06 0:50 ` [PATCH 4/5] x86/fixmap: add a predicate for usermode fixmaps Jeremy Fitzhardinge
2009-10-06 10:23 ` [Xen-devel] " Jan Beulich
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 10:28 ` [Xen-devel] " Jan Beulich
2009-10-06 18:48 ` Jeremy Fitzhardinge
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