New cpufreq framework and drivers

[Colin Percival]

Nate Lawson wrote:
> Hardware drivers are of two types, absolute
> and relative.  SpeedStep, Powernow, etc. are absolute drivers in that 
> they set the cpu's base frequency.  ACPI throttling, Longrun, etc. are 
> relative drivers that reduce the processor's clock to a fraction of its 
> current base (i.e., they have an additive effect.)

If my first glance at the patch is correct, this would have my laptop (a 1.4GHz
Pentium M) reporting the availability of the frequencies 600MHz, 800MHz, etc.
from enhanced speedstep, along with the frequencies 300MHz, 400MHz, 500MHz, and
700MHz obtained via 50% clock throttling.

While this in itself is entirely valid, a clock speed of 700MHz obtained by
running the processor at 1400MHz with a 50% "duty cycle" would draw more power
than a clock speed of 800MHz obtained by running the processor at 800MHz with
a lower voltage; is there any mechanism to inform userland daemons of such
oddities?  I would hate to see a daemon lowering the clock speed from 800MHz
to 700MHz in an attempt to save power...

Colin Percival