linux-kernel - Re: quicklists confuse meminfo

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Message-ID: <20080309121103.3f7019d5@laptopd505.fenrus.org>
Date:	Sun, 9 Mar 2008 12:11:03 -0700
From:	Arjan van de Ven <arjan@...radead.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Lameter <clameter@....com>,
	Bart Van Assche <bart.vanassche@...il.com>
Subject: Re: quicklists confuse meminfo

On Sun, 9 Mar 2008 13:34:32 +0100
Ingo Molnar <mingo@...e.hu> wrote:

> 
> * Ingo Molnar <mingo@...e.hu> wrote:
> 
> > > IMHO we need shrink pgtable cache mecanism.
> > 
> > ouch! Could you try the patch below? How large is the quicklist
> > cache with this applied?
> 
> hm, Thomas pointed it out that this wont solve all the problems as 
> quicklists have a built-in "preserve me" throttle (which is rather 
> stupid).
> 
> the right solution is to get rid of quicklists altogether (Thomas 
> expects to have patches for that later today).

careful with this; the quicklists aren't JUST for speed
they are also there to make sure a page we free that is a pagetable,
is not reused until we have finished flushing the tlbs on all the cpus that saw it.
This is a really hard correctness requirement, and while I can see
that quicklists are probably not the best way to achieve this, we can't just
throw away the behavior ;(

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