linux-kernel - Re: [PATCH 4/7] CPUFREQ: powernow-k8: Get transition latency from ACPI

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Date:	Sun, 08 Feb 2009 12:35:52 -0600
From:	Robert Hancock <hancockrwd@...il.com>
To:	Thomas Renninger <trenn@...e.de>
CC:	davej@...emonkey.org.uk, mark.langsdorf@....com,
	cpufreq@...r.kernel.org, venkatesh.pallipadi@...el.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/7] CPUFREQ: powernow-k8: Get transition latency from
 ACPI _PSS table

Thomas Renninger wrote:
> From: Mark Langsdorf <mark.langsdorf@....com>
> 
> At this time, the PowerNow! driver for K8 uses an experimentally
> derived formula to calculate transition latency.  The value it
> provides is orders of magnitude too large on modern systems.
> This patch replaces the formula with ACPI _PSS latency values
> for more accuracy and better performance.
> 
> I've tested it on two 2nd generation Opteron systems, a 3rd
> generation Operton system, and a Turion X2 without seeing any
> stability problems.
> 
> Signed-off-by: Mark Langsdorf <mark.langsdorf@....com>
> Signed-off-by: Thomas Renninger <trenn@...e.de>
> ---
>  arch/x86/kernel/cpu/cpufreq/powernow-k8.c |   28 ++++++++++++++++++++++------
>  1 files changed, 22 insertions(+), 6 deletions(-)

Hopefully somebody is pushing this for .29? This seems to make a big 
difference in system responsiveness on my Athlon X2 system.
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