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Date: Mon, 23 Feb 2009 12:03:50 -0500 (EST)
From: Christoph Lameter <cl@linux-foundation.org>
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To: Mel Gorman <mel@csn.ul.ie>
cc: Nick Piggin <nickpiggin@yahoo.com.au>,
       Linux Memory Management List <linux-mm@kvack.org>,
       Pekka Enberg <penberg@cs.helsinki.fi>, Rik van Riel <riel@redhat.com>,
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       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Lin Ming <ming.m.lin@intel.com>,
       Zhang Yanmin <yanmin_zhang@linux.intel.com>
Subject: Re: [PATCH 04/20] Convert gfp_zone() to use a table of precalculated
 value
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On Mon, 23 Feb 2009, Mel Gorman wrote:

> > Maybe we can come up with a version of gfp_zone that has no branches and
> > no lookup?
> >
>
> Ideally, yes, but I didn't spot any obvious way of figuring it out at
> compile time then or now. Suggestions?

Can we just mask the relevant bits and then find the highest set bit? With
some rearrangement of gfp flags this may work.