Re: [gpm] CPU throttling based on CPU temperature

[Holger Macht <hmacht suse de>]

On Wed 29. Nov - 11:56:12, Arne John Glenstrup wrote:
> Richard Hughes wrote:
> >On Wed, 2006-11-29 at 11:26 +0100, Arne John Glenstrup wrote:
> 
> >>Couldn't this feature also be possible via hald-addon-cpufreq
> >>and GNOME Power Manager?
> >I don't think it belongs in the UI - it's not a typical use case. Also,
> >you've got to bear in mind it's difficult to identify and process the
> >cpu temperature on all architectures, and 100% reliably.
> 
> OK---after a little more searching, I came across this thread,
> discussing how to get the thermal_zone data into HAL:
> 
> http://lists.freedesktop.org/archives/hal/2006-November/006476.html
> 
> When it gets committed, it would sure be nice to utilise it for noise
> prevention, as in the scenario I described previously.  Although
> perhaps not a typical use case, a checkbox and number field
>  "[x] keep CPU temperature below [__]°C to reduce fan noise"
> could seem like a nicely discreet option.

That's not possible. You never know which termal zone corresponds to your
processor. Currenlty the only possibility to check this is if you look at
/proc/acpi/thermal/*/temperature (or maybe at the HAL properties in
future, load your processor, and see which temperature in which zone
rises. So for every laptop model would need manual intervention.

> I realise that reality isn't quite that simple: what would a
> default temperature be?  How to handle unreliable temperature
> reportings, etc.?

Yes, these are the main problems. Often BIOSes report wrong values.

Just my two cents.

Regards,
	Holger