Re: Laptops & CPU frequency

[John Bradford]

> > > I have an athlon-xp laptop (HP pavilion ze4500) with powernow that
> > > definitely goes into low power mode when the plug is pulled.  The screen
> > > goes dark, and everything slows down.
> > 
> > Dave did not mean that the other power management schemes cannot do the
> > automatic reduction on loss of AC, just that there is no SMM/BIOS hacks
> > to do it automatically.
> 
> People are designing machines where battery can't provide
> enough ampers for cpu in high-power mode. If speedstep machines
> have same problem, SMM is actually right thing to do.

This reminds me of an idea I had years ago, but never really looked in
to very much, (it may well have been implemented somewhere
independently of my idea anyway).  Basically, it was for a multi-cpu
machine which, instead of running cpus in parallel, with all the
common scaling problems, ran each CPU in series for a very short
timeslice, effectively being a uni-processor machine, but moving the
state of the processor's registers between physical CPUs.  The theory
was that it would be possible to clock each CPU much higher for a
short period of time than it could be successfully clocked
continuously.  Physical CPUs with poor cooling could even be given a
shorter timeslice.

John.
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