Re: estd and P-States

[Jukka Ruohonen <jruohonen%iki.fi@localhost>]

On Fri, Sep 03, 2010 at 11:16:02AM +0200, Jes wrote:
> I've been searching information about Enhanced Speed Step and P-States. I
> currently use 'estd' to control the cpu frequency, using '-s' option
> (smooth).  I would launch 'estd' with '-b' option when the laptop is
> running on battery, but I'm not sure if this is supported.

You can easily achieve this by modifying the mentioned acadapter-script. For
instance, when the "released" event is called in powerd(8), stop the estd(1)
daemon and relaunch it with the desired option.

> Why?  well, I can't find any 'sysctl machdep' related to P-States.
 
Unfortunately there has been little planning with different P-state
technologies. Depending on the machine, the sysctl-node is either
machdep.speedstep_state, machdep.est, or machdep.powernow. Possibly some
non-x86 architectures add their own buttons to the mess.

Hopefully these sysctl-knobs and the estd(1) daemon will be some day
deprecated in favour of machine-independent in-kernel implementation.

> In '/etc/powerd/scripts/acadapter' I've seen this piece of code:
> 
>         # Enable power saving mode for speedstep CPUs
>         /sbin/sysctl -w machdep.speedstep_state=0 >/dev/null 2>&1
> 
> But in my laptop there's no such 'machdep.speedstep_state'.

Admittedly, the powerd(8) scripts need some adjustment. (For instance, a
comment in the acadapter-script says that it is a "generic script", but the
script itself goes and does some x86 and vendor-specific things.) I recommend
rewriting these to match your own goals.

> Is there any information about how to configure the C2 state when on
> battery in NetBSD 5.99?

Anything above C1 is not currently supported on NetBSD. As you run -current,
I recommned using the new acpicpu(4) driver (which is presently uncommented in
the normal GENERIC kernels).

- Jukka.