Re: About p4-clockmod breakage/removal

[Len Brown <lenb@kernel.org>]

On Wednesday 14 May 2008, Pavel Troller wrote:
> > On Tue, May 13, 2008 at 08:48:00PM -0400, Len Brown wrote:
> > 
> > > Assuming this is a laptop with a batter,
> > > I'd certainly be interested if you could run BLTK
> > > and measure any benefit to p4-clockmod (I've never
> > > been able to)
> > 
> > The most plausible benefit to p4-clockmod is its utility in throttling 
> > the CPU if it would otherwise cause the system to overheat. From that 
> > point of view, I think it's worth keeping around - especially since not 
> > all machines expose T states via ACPI.
> > 
> Hi!
>   I heavily used p4-clockmod having old, broken battery. Using it and
> throttling the CPU frequency immediately after AC disconnection was
> necessary to limit the maximum current the CPU was able to drain from
> the battery. Otherwise, the battery voltage would drop below the allowed
> level and the machine would either switch off or crash. Yes, in idle state,
> there was no change in the CPU power consumption, but during heavy CPU
> load, 75% throttle really limited the power consumption to the level
> allowing operation even with that old poor battery.
>   So, p4-clockmod REALLY helped me a lot in this case. I vote for keeping
> it on its place!
>   With regards, Pavel Troller

Yes, we could design Linux to be optimal for this broken hardware.
But the cost is that others with actual working hardware
unnwittingly run p4-clockmod and slow down their machine with
no energy savings benefit.

Perhaps there is a different workaround (besides purchasing
a battery or running on AC) that will help you?

Does this machine export /proc/acpi/processor/*/throttling?

-Len