what is 'cpuspeed' for?

[Satish Balay]

On Mon, 3 Jan 2005, Satish Balay wrote:
> On Mon, 3 Jan 2005, Satish Balay wrote:
> > On Mon, 3 Jan 2005, Dave Jones wrote:
> > 
> > >  > 'cpuspeed' needs to support '--ignore-intermediate-frequencies' option
> > >  > to speed up the transtiton between max & min speeds.
> > > 
> > > It can't. Some implementations of speed scaling can't handle
> > > huge leaps, and need to be 'stepped'. Some of the drivers do this
> > > internally anyway, so even if you removed it from cpuspeed, the
> > > multiple transitions would still be occuring.
> > 
> > I guess internal multiple transitions is fine. But looks like cpuspeed
> > is not taking advantage of it.
> > 
> > Each transition is a single step (600 -> 800 -> 1000 etc..) - and each
> > step occurs only ater the requisite '-i' interaval.
> 
> (to add some perspective) - I've used cpudyn on FC1 - and I liked
> it. (However it doesn't work with fedora 2.6 kernels - hence using
> cpuspeed)
> 
> http://mnm.uib.es/gallir/cpudyn/faq.html
> The cpudyn FAQ has the following text:
> 
> 7. Whay does it have just two states: powersave and performance? Why
> don't you allow to specify other frequencies.
> 
> Basically because I dont need it. I just need these two states, go to
> the maximum when it's needed it. Go to the minimum if it's not
> needed. cpudynd is very good at reacting interactively to the CPU
> load.

Another datapoint from 'powernowd' (Trevor alluded to). From the README:

---
Mode 3, LEAPS : Immediately jump to the highest frequency if usage above 80%.
                Immediately jump to the lowest frequency if usage below 20%.
---

Satish