linux-kernel - Re: [PATCH RFC 1/2] kvm: Handle undercommitted guest case in PLE handler

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Message-ID: <50608994.3050004@redhat.com>
Date:	Mon, 24 Sep 2012 18:25:56 +0200
From:	Avi Kivity <avi@...hat.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>,
	Rik van Riel <riel@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
	Marcelo Tosatti <mtosatti@...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 1/2] kvm: Handle undercommitted guest case in PLE
 handler

On 09/24/2012 06:14 PM, Peter Zijlstra wrote:
> On Mon, 2012-09-24 at 18:06 +0200, Avi Kivity wrote:
>> 
>> We would probably need a ->sched_exit() preempt notifier to make this
>> work.  Peter, I know how much you love those, would it be acceptable? 
> 
> Where exactly do you want this? TASK_DEAD? or another exit?

TASK_DEAD of the task that registered the preempt notifier.

The idea is that I want to hold on to the notifier even when exiting to
userspace.  Since userspace is under no obligation to call kvm again, I
need a chance to unregister the notifier and otherwise clean up.

Eh, looking at the code, we'll have a ->sched_out() after the state is
set to TASK_DEAD.  So all we need to do is examine the state.  We'll
need to examine the state anyway to see if we were preempted or blocking.

-- 
error compiling committee.c: too many arguments to function
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