Cx states not working on Dell Inspiron 8600 (Pentium M)

[Kevin Oberman]

> Date: Thu, 26 Aug 2004 11:42:08 +0200
> From: Ulrich Spoerlein <q at uni.de>
> Sender: owner-freebsd-acpi at freebsd.org
> 
> 
> --wzJLGUyc3ArbnUjN
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> 
> Hello,
> 
> I've been running CURRENT on this laptop since the gcc 3.4 import and
> the Cx states don't work (AFAICS).
> 
> dmesg, kernel config, DSDT and ASL can be obtained from
> http://www.galgenberg.net/~q/freebsd
> 
> No matter if I pull the AC-plug or not, I get this:
> hw.acpi.cpu.throttle_max: 8
> hw.acpi.cpu.throttle_state: 8
> hw.acpi.cpu.cx_supported: C1/1 C2/1 C3/85 C4/185
> hw.acpi.cpu.cx_lowest: C4
> hw.acpi.cpu.cx_usage: 0.00% 100.00% 0.00% 0.00%
> 
> As a result the laptop runs rather hot and the battery life is limited
> (compared to Windows)
> 
> Am I using the wrong semantics for cx_lowest or throttle_max?

The cx_usage is limited to C1 or C2 if USB is loaded. It's polling of
the bus for changes prevents the state from dropping to anything really
useful. If you don't always need USB, build a kernel without it and load
it as required.

What do you have in your rc.conf? The default for economy_throttle_state
is "HIGH" which is probably not what you want. Not knowing how fast your
CPU is or how you use it, I don't know where you want to set it.  

Try experimenting with:
sysctl hw.acpi.cpu.throttle_state=n
setting 'n' to values in the range of 1-8 and see where you think it's
reasonable to get work done without draining the battery. I use:
economy_throttle_state=4. Any lower and things start to get painful for
me. 
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634