linux-kernel - Re: [PATCH RFC 2/2] kvm: Be courteous to other VMs in overcommitted scenario in PLE handler

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Message-ID: <50618361.4070006@redhat.com>
Date:	Tue, 25 Sep 2012 12:11:45 +0200
From:	Avi Kivity <avi@...hat.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Ingo Molnar <mingo@...hat.com>, Rik van Riel <riel@...hat.com>,
	Srikar <srikar@...ux.vnet.ibm.com>,
	"Nikunj A. Dadhania" <nikunj@...ux.vnet.ibm.com>,
	KVM <kvm@...r.kernel.org>, Jiannan Ouyang <ouyang@...pitt.edu>,
	chegu vinod <chegu_vinod@...com>,
	"Andrew M. Theurer" <habanero@...ux.vnet.ibm.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Srivatsa Vaddagiri <srivatsa.vaddagiri@...il.com>,
	Gleb Natapov <gleb@...hat.com>
Subject: Re: [PATCH RFC 2/2] kvm: Be courteous to other VMs in overcommitted
 scenario in PLE handler

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.

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