From: Jes Sorensen <Jes.Sorensen@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>,
Avi Kivity <avi@redhat.com>, LKML <linux-kernel@vger.kernel.org>,
kvm@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
Fr??d??ric Weisbecker <fweisbec@gmail.com>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Cyrill Gorcunov <gorcunov@gmail.com>,
Lin Ming <ming.m.lin@intel.com>,
Sheng Yang <sheng@linux.intel.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
oerg Roedel <joro@8bytes.org>, Gleb Natapov <gleb@redhat.com>,
Zachary Amsden <zamsden@redhat.com>,
zhiteng.huang@intel.com, tim.c.chen@intel.com
Subject: Re: [PATCH V2 1/5] ara virt interface of perf to support kvm guest os statistics collection in guest os
Date: Tue, 22 Jun 2010 11:39:07 +0200 [thread overview]
Message-ID: <4C2084BB.3040501@redhat.com> (raw)
In-Reply-To: <1277199060.1875.675.camel@laptop>
On 06/22/10 11:31, Peter Zijlstra wrote:
> On Tue, 2010-06-22 at 17:29 +0800, Zhang, Yanmin wrote:
>> On Tue, 2010-06-22 at 10:00 +0200, Jes Sorensen wrote:
>>> On 06/22/10 09:55, Peter Zijlstra wrote:
>>>> On Tue, 2010-06-22 at 15:47 +0800, Zhang, Yanmin wrote:
>>>>> Besides the para virt perf interface, I'm also considering the direct exposition
>>>>> of PMU hardware to guest os.
>>>>
>>>> NAK NAK NAK NAK, we've been over that, its not going to happen, full
>>>> stop!
>>>>
>>>> Use MSR read/write traps and host perf to emulate the hardware. In some
>>>> cases we could allow the reads without trap but that's a later
>>>> optimization.
>>>
>>> I believe whats meant here is a PMU compatible interface which is
>>> partially emulated. Not a handover of the PMU.
>> Right. We need capture all write to PMU MSR and allows guest os to read MSR directly.
>
> That latter is not possible, only in a subset of cases can you allow
> that read.
Avi's suggestion of using virtual MSRs makes a ton of sense for this
though, and it makes it possible to switch direct access on/off for the
cases where direct access is possible, and go emulated when it isn't.
Cheers,
Jes
next prev parent reply other threads:[~2010-06-22 9:39 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-21 9:31 [PATCH V2 1/5] ara virt interface of perf to support kvm guest os statistics collection in guest os Zhang, Yanmin
2010-06-21 11:45 ` Avi Kivity
2010-06-22 1:49 ` Zhang, Yanmin
2010-06-22 7:14 ` Jes Sorensen
2010-06-22 7:47 ` Zhang, Yanmin
2010-06-22 7:55 ` Peter Zijlstra
2010-06-22 8:00 ` Jes Sorensen
2010-06-22 9:29 ` Zhang, Yanmin
2010-06-22 9:31 ` Peter Zijlstra
2010-06-22 9:39 ` Jes Sorensen [this message]
2010-06-22 9:46 ` Peter Zijlstra
2010-06-22 9:53 ` Avi Kivity
2010-06-22 10:02 ` Peter Zijlstra
2010-06-22 10:06 ` Avi Kivity
2010-06-22 10:10 ` Peter Zijlstra
2010-06-22 11:01 ` Avi Kivity
2010-06-22 7:58 ` Jes Sorensen
2010-06-23 1:13 ` Zhang, Yanmin
2010-06-23 8:15 ` Jes Sorensen
2010-06-22 8:59 ` Avi Kivity
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