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Date: Mon, 23 Feb 2009 11:33:00 -0500 (EST)
From: Christoph Lameter <cl@linux-foundation.org>
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To: Mel Gorman <mel@csn.ul.ie>
cc: Linux Memory Management List <linux-mm@kvack.org>,
       Pekka Enberg <penberg@cs.helsinki.fi>, Rik van Riel <riel@redhat.com>,
       KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
       Johannes Weiner <hannes@cmpxchg.org>, Nick Piggin <npiggin@suse.de>,
       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:

> I was concerned with mispredictions here rather than the actual assembly
> and gfp_zone is inlined so it's lot of branches introduced in a lot of paths.

The amount of speculation that can be done by the processor pretty
limited to a few instructions. So the impact of a misprediction also
should be minimal. The decoder is likely to have sucked in the following
code anyways.