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Date: Tue, 25 Sep 2012 12:11:45 +0200
From: Avi Kivity <avi@redhat.com>
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To: Peter Zijlstra <peterz@infradead.org>
CC: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Marcelo Tosatti <mtosatti@redhat.com>, Ingo Molnar <mingo@redhat.com>,
        Rik van Riel <riel@redhat.com>, Srikar <srikar@linux.vnet.ibm.com>,
        "Nikunj A. Dadhania" <nikunj@linux.vnet.ibm.com>,
        KVM <kvm@vger.kernel.org>, Jiannan Ouyang <ouyang@cs.pitt.edu>,
        chegu vinod <chegu_vinod@hp.com>,
        "Andrew M. Theurer" <habanero@linux.vnet.ibm.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Srivatsa Vaddagiri <srivatsa.vaddagiri@gmail.com>,
        Gleb Natapov <gleb@redhat.com>
Subject: Re: [PATCH RFC 2/2] kvm: Be courteous to other VMs in overcommitted
 scenario in PLE handler
References: <20120921115942.27611.67488.sendpatchset@codeblue>     <20120921120019.27611.66093.sendpatchset@codeblue>     <50607BBE.8070507@redhat.com> <1348500861.11847.72.camel@twins>    <50607F9B.7090701@redhat.com> <1348501929.11847.81.camel@twins>   <50608323.9000603@redhat.com> <1348502757.11847.91.camel@twins>  <50608608.4000507@redhat.com> <1348503219.11847.98.camel@twins> <50608887.7050204@redhat.com>
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On 09/24/2012 06:21 PM, Avi Kivity wrote:
> On 09/24/2012 06:13 PM, Peter Zijlstra wrote:
> > On Mon, 2012-09-24 at 18:10 +0200, Avi Kivity wrote:
> >> > Its also still a LAPIC write -- disguised as an MSR though :/
> >> 
> >> It's probably a whole lot faster though. 
> > 
> > I've been told its not, I haven't tried it.
>
> I'll see if I can find a machine with it (don't see it on my Westmere,
> it's probably on one of the Bridges.  Or maybe the other Peter knows.
>
>

Before measuring TSC_DEADLINE, I measured writing to TMICT, it costs 32
cycles.  This is on a Sandy Bridge.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.