Re: [PATCH 4/7] CPUFREQ: powernow-k8: Get transition latency fromACPI _PSS table

From: Robert Hancock
Date: Sun Feb 08 2009 - 13:36:15 EST


Thomas Renninger wrote:
From: Mark Langsdorf <mark.langsdorf@xxxxxxx>

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@xxxxxxx>
Signed-off-by: Thomas Renninger <trenn@xxxxxxx>
---
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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