From: Jes Sorensen <Jes.Sorensen@redhat.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Avi Kivity <avi@redhat.com>, Joerg Roedel <joro@8bytes.org>,
KVM General <kvm@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Zachary Amsden <zamsden@redhat.com>,
Gleb Natapov <gleb@redhat.com>,
ming.m.lin@intel.com, "Zhang,
Yanmin" <yanmin_zhang@linux.intel.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Arjan van de Ven <arjan@infradead.org>,
Fr??d??ric Weisbecker <fweisbec@gmail.com>,
Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: Re: KVM PMU virtualization
Date: Fri, 26 Feb 2010 14:37:23 +0100 [thread overview]
Message-ID: <4B87CE93.1070906@redhat.com> (raw)
In-Reply-To: <20100226133149.GA23422@elte.hu>
On 02/26/10 14:31, Ingo Molnar wrote:
> You are missing two big things wrt. compatibility here:
>
> 1) The first upgrade overhead a one time overhead only.
>
> 2) Once a Linux guest has upgraded, it will work in the future, with _any_
> future CPU - _without_ having to upgrade the guest!
>
> Dont you see the advantage of that? You can instrument an old system on new
> hardware, without having to upgrade that guest for the new CPU support.
That would only work if you are guaranteed to be able to emulate old
hardware on new hardware. Not going to be feasible, so then we are in a
real mess.
> With the 'steal the PMU' messy approach the guest OS has to be upgraded to the
> new CPU type all the time. Ad infinitum.
The way the Perfmon architecture is specified by Intel, that is what we
are stuck with. It's not going to be possible via software emulation to
count cache misses, unless you run it in a micro architecture emulator.
Jes
next prev parent reply other threads:[~2010-02-26 13:38 UTC|newest]
Thread overview: 99+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-25 15:04 KVM PMU virtualization Jes Sorensen
2010-02-25 15:44 ` Jan Kiszka
2010-02-25 16:26 ` Ingo Molnar
2010-02-26 2:52 ` Zhang, Yanmin
2010-02-26 8:45 ` Ingo Molnar
2010-02-26 11:03 ` Jes Sorensen
2010-02-25 17:34 ` Joerg Roedel
2010-02-26 2:55 ` Zhang, Yanmin
2010-02-26 8:51 ` Joerg Roedel
2010-02-26 9:17 ` Ingo Molnar
2010-02-26 10:42 ` Joerg Roedel
2010-02-26 10:56 ` Ingo Molnar
2010-03-02 7:09 ` Zhang, Yanmin
2010-03-02 9:36 ` Ingo Molnar
2010-03-03 3:32 ` Zhang, Yanmin
2010-03-03 9:27 ` Zhang, Yanmin
2010-03-03 10:13 ` Peter Zijlstra
2010-03-04 0:52 ` Zhang, Yanmin
2010-03-03 10:15 ` Peter Zijlstra
2010-03-04 1:00 ` Zhang, Yanmin
2010-03-10 9:29 ` Zhang, Yanmin
2010-03-02 9:57 ` Peter Zijlstra
2010-02-26 8:42 ` Ingo Molnar
2010-02-26 9:46 ` Avi Kivity
2010-02-26 10:39 ` Joerg Roedel
2010-02-26 10:46 ` Ingo Molnar
2010-02-26 10:51 ` Avi Kivity
2010-02-26 11:06 ` Joerg Roedel
2010-02-26 11:18 ` Jes Sorensen
2010-02-26 11:24 ` Ingo Molnar
2010-02-26 11:25 ` Jes Sorensen
2010-02-26 11:20 ` Ingo Molnar
2010-02-26 10:44 ` Ingo Molnar
2010-02-26 11:16 ` Avi Kivity
2010-02-26 11:26 ` Ingo Molnar
2010-02-26 11:47 ` Avi Kivity
2010-02-26 11:23 ` Jes Sorensen
2010-02-26 11:42 ` Ingo Molnar
2010-02-26 11:51 ` Avi Kivity
2010-02-26 12:07 ` Ingo Molnar
2010-02-26 12:20 ` Avi Kivity
2010-02-26 12:38 ` Ingo Molnar
2010-02-26 13:04 ` Avi Kivity
2010-02-26 13:13 ` Jes Sorensen
2010-02-26 13:27 ` Ingo Molnar
2010-02-26 13:33 ` Avi Kivity
2010-02-26 14:07 ` Jes Sorensen
2010-02-26 14:11 ` Avi Kivity
2010-02-26 13:18 ` Ingo Molnar
2010-02-26 13:34 ` Jes Sorensen
2010-02-26 12:56 ` Jes Sorensen
2010-02-26 13:31 ` Ingo Molnar
2010-02-26 13:37 ` Jes Sorensen [this message]
2010-02-26 13:55 ` Avi Kivity
2010-02-26 14:27 ` Peter Zijlstra
2010-02-26 14:54 ` Avi Kivity
2010-02-26 15:08 ` Peter Zijlstra
2010-02-26 15:11 ` Avi Kivity
2010-02-26 15:18 ` Peter Zijlstra
2010-02-26 15:55 ` Peter Zijlstra
2010-02-26 16:06 ` Avi Kivity
2010-03-01 19:03 ` Zachary Amsden
2010-03-01 18:54 ` Zachary Amsden
2010-02-26 13:40 ` Avi Kivity
2010-02-26 14:01 ` Ingo Molnar
2010-02-26 14:22 ` Avi Kivity
2010-02-26 14:37 ` Ingo Molnar
2010-02-26 16:03 ` Avi Kivity
2010-02-26 16:07 ` Avi Kivity
2010-02-26 13:28 ` Peter Zijlstra
2010-02-26 13:44 ` Avi Kivity
2010-02-26 13:51 ` Jes Sorensen
2010-02-26 14:42 ` Peter Zijlstra
2010-03-08 18:14 ` Avi Kivity
2010-02-26 12:49 ` Jes Sorensen
2010-02-26 13:06 ` Ingo Molnar
2010-02-26 13:30 ` Avi Kivity
2010-02-26 13:32 ` Jes Sorensen
2010-02-26 13:44 ` Ingo Molnar
2010-02-26 13:53 ` Avi Kivity
2010-02-26 14:12 ` Ingo Molnar
2010-02-26 14:53 ` Avi Kivity
2010-02-26 15:14 ` Peter Zijlstra
2010-02-28 16:34 ` Joerg Roedel
2010-02-28 16:31 ` Joerg Roedel
2010-02-28 16:11 ` Joerg Roedel
2010-03-01 8:39 ` Ingo Molnar
2010-03-01 8:58 ` Joerg Roedel
2010-03-01 9:04 ` Ingo Molnar
2010-03-01 8:44 ` Ingo Molnar
2010-03-01 11:11 ` Joerg Roedel
2010-03-01 17:17 ` Peter Zijlstra
2010-03-01 18:36 ` Joerg Roedel
2010-03-08 10:15 ` Avi Kivity
2010-02-26 14:49 ` Peter Zijlstra
2010-02-26 14:50 ` Peter Zijlstra
2010-02-26 13:31 ` Jes Sorensen
2010-03-01 17:22 ` Zachary Amsden
2010-02-26 11:01 ` Jes Sorensen
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