From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 9 Dec 2008 20:43:39 +0000 (+0100)
Subject: perf counters: protect them against CSTATE transitions
X-Git-Tag: v2.6.31-rc1~383^2~582
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4ac13294e44664bb7edf4daf52edb71e7c6bbe84;p=pandora-kernel.git

perf counters: protect them against CSTATE transitions

Impact: fix rare lost events problem

There are CPUs whose performance counters misbehave on CSTATE transitions,
so provide a way to just disable/enable them around deep idle methods.

(hw_perf_enable_all() is cheap on x86.)

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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