From: Avi Kivity <avi@redhat.com>
To: Sheng Yang <sheng@linux.intel.com>
Cc: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>,
Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Marcelo Tosatti <mtosatti@redhat.com>,
oerg Roedel <joro@8bytes.org>,
Jes Sorensen <Jes.Sorensen@redhat.com>,
Gleb Natapov <gleb@redhat.com>,
Zachary Amsden <zamsden@redhat.com>,
zhiteng.huang@intel.com, tim.c.chen@intel.com,
Arnaldo Carvalho de Melo <acme@infradead.org>
Subject: Re: [PATCH V3] perf & kvm: Enhance perf to collect KVM guest os statistics from host side
Date: Wed, 14 Apr 2010 13:19:49 +0300 [thread overview]
Message-ID: <4BC596C5.7020507@redhat.com> (raw)
In-Reply-To: <201004141814.19330.sheng@linux.intel.com>
On 04/14/2010 01:14 PM, Sheng Yang wrote:
>
>> I wouldn't like to depend on model specific behaviour.
>>
>> One option is to read all the information synchronously and store it in
>> a per-cpu area with atomic instructions, then queue the NMI. Another
>> option is to have another callback which tells us that the NMI is done,
>> and have a busy loop wait until the NMI is delivered.
>>
>>
> Callback seems too heavy, may affect the performance badly. Maybe a short
> queue would help, though this one is more complex.
>
The patch we're replying to adds callbacks (to read rip, etc.), so it's
no big deal. For the queue solution, a queue of size one would probably
be sufficient even if not guaranteed by the spec. I don't see how the
cpu can do another guest entry without delivering the NMI.
> But I am still curious if we extend the region, how much it would help. Would
> get a result soon...
>
Yes, interesting to see what the latency is. If it's reasonably short
(and I expect it will be so), we can do the busy wait solution.
If we have an NMI counter somewhere, we can simply wait until it changes.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2010-04-14 10:20 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2030-04-14 9:05 [PATCH V3] perf & kvm: Enhance perf to collect KVM guest os statistics from host side Zhang, Yanmin
2010-04-14 9:20 ` Avi Kivity
2010-04-14 9:43 ` Sheng Yang
2010-04-14 9:57 ` Avi Kivity
2010-04-14 10:14 ` Sheng Yang
2010-04-14 10:19 ` Avi Kivity [this message]
2010-04-14 10:27 ` Sheng Yang
2010-04-14 10:33 ` Avi Kivity
2010-04-14 10:36 ` Sheng Yang
2010-04-14 10:43 ` Ingo Molnar
2010-04-14 11:17 ` Avi Kivity
2030-04-15 1:04 ` Zhang, Yanmin
2010-04-15 8:05 ` Avi Kivity
2030-04-15 8:57 ` Zhang, Yanmin
2010-04-15 9:04 ` oerg Roedel
2010-04-15 9:09 ` Avi Kivity
2010-04-15 9:44 ` oerg Roedel
2010-04-15 9:48 ` Avi Kivity
2010-04-15 10:40 ` Joerg Roedel
2010-04-15 10:44 ` Avi Kivity
2010-04-15 14:08 ` Sheng Yang
2010-04-17 18:12 ` Avi Kivity
2010-04-19 8:25 ` Avi Kivity
2010-04-20 3:32 ` Sheng Yang
2010-04-20 9:38 ` Avi Kivity
2010-04-27 19:03 ` [PATCH] Psychovisually-optimized HZ setting (2.6.33.3) Uwaysi Bin Kareem
2010-04-27 19:51 ` Randy Dunlap
2010-04-27 21:50 ` Valdis.Kletnieks
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