From mboxrd@z Thu Jan  1 00:00:00 1970
From: Takuya Yoshikawa <takuya.yoshikawa@gmail.com>
Subject: Re: [PATCH RFC 1/2] kvm: Handle undercommitted guest case in PLE
 handler
Date: Tue, 25 Sep 2012 23:21:22 +0900
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Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
	Rik van Riel <riel@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
	Marcelo Tosatti <mtosatti@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>
To: Avi Kivity <avi@redhat.com>
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On Tue, 25 Sep 2012 10:12:49 +0200
Avi Kivity <avi@redhat.com> wrote:

> It will.  The tradeoff is between false-positive costs (undercommit) and
> true positive costs (overcommit).  I think undercommit should perform
> well no matter what.
> 
> If we utilize preempt notifiers to track overcommit dynamically, then we
> can vary the spin time dynamically.  Keep it long initially, as we get
> more preempted vcpus make it shorter.

What will happen if we pin each vcpu thread to some core?
I don't want to see so many vcpu threads moving around without
being pinned at all.

In that case, we don't want to make KVM do any work of searching
a vcpu thread to yield to.

Thanks,
	Takuya