linux-kernel - Re: quicklists confuse meminfo

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Message-ID: <20080310190611.GA9246@one.firstfloor.org>
Date:	Mon, 10 Mar 2008 20:06:11 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
Cc:	Andi Kleen <andi@...stfloor.org>, Hugh Dickins <hugh@...itas.com>,
	Christoph Lameter <clameter@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Bart Van Assche <bart.vanassche@...il.com>
Subject: Re: quicklists confuse meminfo

On Mon, Mar 10, 2008 at 11:35:50AM -0700, Jeremy Fitzhardinge wrote:
> Hm, given that Xen doesn't make any topology guarantees about vcpus, I 
> don't think it would make much difference.  I think it would only be 
> observable if you actually pinned the vcpus to physical siblings.  
> Besides we could easily maintain sibling info and look to see if we're 
> about to reload cr3 to match the other thread(s), then just use the same 
> pgd copy.

The optimization doesn't really require any topology information; 
you just should make sure that if you have a VM shared between
different CPUs that it has the same CR3. The easiest way to enforce
that is to always only use a single CR3 for a VM.

-Andi
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