From 4ac3a3e2845648ddbfdf62dde6eb5e50eb1b4a8c Mon Sep 17 00:00:00 2001
From: Borislav Petkov <borislav.petkov@amd.com>
Date: Thu, 17 Feb 2011 14:57:02 +0100
Subject: [PATCH] x86, hotplug: Fix powersavings with offlined cores on AMD

Upstream commits: 93789b32dbf355e70f18b17a82e8661677a7f7fb,
	 1c9d16e35911090dee3f9313e6af13af623d66ee

ea53069231f9317062910d6e772cca4ce93de8c8 made a CPU use monitor/mwait
when offline. This is not the optimal choice for AMD wrt to powersavings
and we'd prefer our cores to halt (i.e. enter C1) instead. For this, the
same selection whether to use monitor/mwait has to be used as when we
select the idle routine for the machine.

With this patch, offlining cores 1-5 on a X6 machine allows core0 to
boost again.

[ hpa: putting this in urgent since it is a (power) regression fix ]

Reported-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Venkatesh Pallipadi <venki@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.hl>
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
LKML-Reference: <1295534572-10730-1-git-send-email-bp@amd64.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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