From: Sheng Yang <sheng@linux.intel.com>
Organization: Intel Opensource Technology Center
To: Avi Kivity <avi@redhat.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
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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>
References: <1902387910.2078.435.camel@ymzhang.sh.intel.com> <201004141827.21877.sheng@linux.intel.com> <4BC59A01.3070802@redhat.com>
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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
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