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Date: Wed, 3 Nov 2010 22:47:33 +0530
From: Balbir Singh <balbir@linux.vnet.ibm.com>
Message-ID: <20101103171733.GP3769@balbir.in.ibm.com>
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Subject: [Qemu-devel] Re: [RFC][PATCH 1/3] Linux/Guest unmapped page cache
	control
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To: Christoph Lameter <cl@linux.com>
Cc: linux-mm@kvack.org, qemu-devel@nongnu.org, kvm@vger.kernel.org

* Christoph Lameter <cl@linux.com> [2010-11-03 09:35:33]:

> On Fri, 29 Oct 2010, Balbir Singh wrote:
> 
> > A lot of the code is borrowed from zone_reclaim_mode logic for
> > __zone_reclaim(). One might argue that the with ballooning and
> > KSM this feature is not very useful, but even with ballooning,
> 
> Interesting use of zone reclaim. I am having a difficult time reviewing
> the patch since you move and modify functions at the same time. Could you
> separate that out a bit?
>

Sure, I'll split it out into more readable bits and repost the mm
versions first.
 
> > +#define UNMAPPED_PAGE_RATIO 16
> 
> Maybe come up with a scheme that allows better configuration of the
> mininum? I think in some setting we may want an absolute limit and in
> other a fraction of something (total zone size or working set?)
>

Are you suggesting a sysctl or computation based on zone size and
limit, etc? I understand it to be the latter.
 
> 
> > +bool should_balance_unmapped_pages(struct zone *zone)
> > +{
> > +	if (unmapped_page_control &&
> > +		(zone_unmapped_file_pages(zone) >
> > +			UNMAPPED_PAGE_RATIO * zone->min_unmapped_pages))
> > +		return true;
> > +	return false;
> > +}
> 

Thanks for your review.

-- 
	Three Cheers,
	Balbir