From mboxrd@z Thu Jan  1 00:00:00 1970
From: Sheng Yang <sheng@linux.intel.com>
Subject: Re: [PATCH V3] perf & kvm: Enhance perf to collect KVM guest os statistics from host side
Date: Wed, 14 Apr 2010 18:36:07 +0800
Message-ID: <201004141836.07477.sheng@linux.intel.com>
References: <1902387910.2078.435.camel@ymzhang.sh.intel.com> <201004141827.21877.sheng@linux.intel.com> <4BC59A01.3070802@redhat.com>
Mime-Version: 1.0
Content-Type: Text/Plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
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>
To: Avi Kivity <avi@redhat.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <4BC59A01.3070802@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
List-Id: kvm.vger.kernel.org

On Wednesday 14 April 2010 18:33:37 Avi Kivity wrote:
> On 04/14/2010 01:27 PM, Sheng Yang wrote:
> >> 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.
> >
> > Good idea. Of course we have one(at least on x86). There is
> > irq_stat.irq__nmi_count for per cpu. :)
> 
> Okay, but kvm doesn't want to know about it.  How about a new arch
> function, invoke_nmi_sync(), that will trigger the NMI and wait for it?
> 
Sound reasonable. Would try it.

-- 
regards
Yang, Sheng