Date: Wed, 1 Dec 2010 09:01:32 -0600 (CST)
From: Christoph Lameter <cl@linux.com>
To: Andrew Morton <akpm@linux-foundation.org>
cc: Balbir Singh <balbir@linux.vnet.ibm.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, kvm <kvm@vger.kernel.org>
Subject: Re: [PATCH 3/3] Provide control over unmapped pages
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On Tue, 30 Nov 2010, Andrew Morton wrote:

> > +#define UNMAPPED_PAGE_RATIO 16
>
> Well.  Giving 16 a name didn't really clarify anything.  Attentive
> readers will want to know what this does, why 16 was chosen and what
> the effects of changing it will be.

The meaning is analoguous to the other zone reclaim ratio. But yes it
should be justified and defined.

> > Reviewed-by: Christoph Lameter <cl@linux.com>
>
> So you're OK with shoving all this flotsam into 100,000,000 cellphones?
> This was a pretty outrageous patchset!

This is a feature that has been requested over and over for years. Using
/proc/vm/drop_caches for fixing situations where one simply has too many
page cache pages is not so much fun in the long run.

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