From: Arjan van de Ven <arjan@linux.intel.com>
Date: Sun, 9 May 2010 15:26:51 +0000 (-0700)
Subject: ondemand: Make the iowait-is-busy time a sysfs tunable
X-Git-Tag: v2.6.35-rc1~521^2~3
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=19379b11819efc1fc3b602e64f7e7531050aaddb;p=pandora-kernel.git

ondemand: Make the iowait-is-busy time a sysfs tunable

Pavel Machek pointed out that not all CPUs have an efficient
idle at high frequency. Specifically, older Intel and various
AMD cpus would get a higher powerusage when copying files from
USB.

Mike Chan pointed out that the same is true for various ARM
chips as well.

Thomas Renninger suggested to make this a sysfs tunable with a
reasonable default.

This patch adds a sysfs tunable for the new behavior, and uses
a very simple function to determine a reasonable default,
depending on the CPU vendor/type.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: davej@redhat.com
LKML-Reference: <20100509082651.46914d04@infradead.org>
[ minor tidyup ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

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