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Date:	Fri, 28 Sep 2012 16:13:05 +0200
From:	Peter Zijlstra <>
Cc:	Raghavendra K T <>,
	Avi Kivity <>, "H. Peter Anvin" <>,
	Marcelo Tosatti <>,
	Ingo Molnar <>, Rik van Riel <>,
	Srikar <>,
	"Nikunj A. Dadhania" <>,
	KVM <>, Jiannan Ouyang <>,
	chegu vinod <>,
	LKML <>,
	Srivatsa Vaddagiri <>,
	Gleb Natapov <>,
	Andrew Jones <>
Subject: Re: [PATCH RFC 0/2] kvm: Improving undercommit,overcommit scenarios
 in PLE handler

On Fri, 2012-09-28 at 06:40 -0500, Andrew Theurer wrote:
> It will be interesting to see how this behaves with a very high lock
> activity in a guest.  Once the scheduler defers preemption, is it for
> a
> fixed amount of time, or does it know to cut the deferral short as
> soon
> as the lock depth is reduced [by x]? 

Since the locks live in a guest/userspace, we don't even know they're
held at all, let alone when state changes.

Also, afaik PLE simply exits the guest whenever you do a busy-wait,
there's no guarantee its due to a lock at all, we could be waiting for a
'virtual' hardware resource or whatnot.

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