Date: Mon, 6 Aug 2007 22:12:52 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: mel@skynet.ie (Mel Gorman)
Cc: Andi Kleen <ak@suse.de>, Lee.Schermerhorn@hp.com, clameter@sgi.com,
       kamezawa.hiroyu@jp.fujitsu.com, linux-mm@kvack.org,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Apply memory policies to top two highest zones when
 highest zone is ZONE_MOVABLE
Message-Id: <20070806221252.aa1e9048.akpm@linux-foundation.org>
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On Mon, 6 Aug 2007 22:55:41 +0100 mel@skynet.ie (Mel Gorman) wrote:

> On (06/08/07 22:31), Andi Kleen didst pronounce:
> > 
> > > If correct, I would suggest merging the horrible hack for .23 then taking
> > > it out when we merge "grouping pages by mobility".  But what if we don't do
> > > that merge?
> > 
> > Or disable ZONE_MOVABLE until it is usable?
> 
> It's usable now. The issue with policies only occurs if the user specifies
> kernelcore= or movablecore= on the command-line. Your language suggests
> that you believe policies are not applied when ZONE_MOVABLE is configured
> at build-time.

So..  the problem which we're fixing here is only present when someone
use kernelcore=.  This is in fact an argument for _not_ merging the
horrible-hack.

How commonly do we expect people to specify kernelcore=?  If "not much" then
it isn't worth adding the __alloc_pages() overhead?

(It's a pretty darn small overhead, I must say)
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