From: Rusty Russell <rusty@rustcorp.com.au>
Date: Tue, 12 Aug 2008 22:52:53 +0000 (-0500)
Subject: lguest: use get_user_pages_fast() instead of get_user_pages()
X-Git-Tag: v2.6.27-rc3~46^2~4
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=71a3f4edc11b9dd7af28d003acbbd33496003da1;p=pandora-kernel.git

lguest: use get_user_pages_fast() instead of get_user_pages()

Using a simple page table thrashing program I measure a slight
improvement.  The program creates five processes.  Each touches 1000
pages then schedules the next process.  We repeat this 1000 times.  As
lguest only caches 4 cr3 values, this rebuilds a lot of shadow page
tables requiring virt->phys mappings.

	Before: 5.93 seconds
	After: 5.40 seconds

(Counts of slow vs fastpath in this usage are 6092 and 2852462 respectively.)

And more importantly for lguest, the code is simpler.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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