linux-kernel - Re: [PATCH 02/11] Add "handle page fault" PV helper.

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Message-ID: <20091108130521.GA29728@elte.hu>
Date:	Sun, 8 Nov 2009 14:05:21 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Avi Kivity <avi@...hat.com>
Cc:	Gleb Natapov <gleb@...hat.com>, kvm@...r.kernel.org,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Fr??d??ric Weisbecker <fweisbec@...il.com>
Subject: Re: [PATCH 02/11] Add "handle page fault" PV helper.


* Avi Kivity <avi@...hat.com> wrote:

> On 11/08/2009 02:51 PM, Ingo Molnar wrote:
> >>Maybe we should generalize paravirt-ops patching in case if (x) f() is
> >>deemed too expensive.
> >Yes, that's a nice idea. We have quite a number of 'conditional
> >callbacks' in various critical paths that could be made lighter via such
> >a technique.
> >
> > It would also free new callbacks from the 'it increases overhead 
> > even if unused' criticism and made it easier to add them.
> 
> We can take the "immediate values" infrastructure as a first step. Has 
> that been merged?

No, there were doubts about whether patching in live instructions like 
that is safe on all CPU types.

	Ingo
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