[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: Searching Tool for CPU stepping down

On Thu, Jul 27, 2006 at 07:14:00PM +0200, Hans-J. Ullrich wrote:
> Hi all, 
> today I have an unusual thouhgt: I am looking for a tool, which I want to 
> start on the notebook, when doing nothing. I do NOT mean powernowd, cpufreqd 
> or similar, which use the pins on the cpu to switch it down (on my AMD-Turion 
> to 800MHz) I am looking for a tool like those on windows in the early 486er 
> days: they were called "waterfall" or "raindrop" and could change the 
> cycle-rate from i.e. 100 MHz to 10 MHz. 

Nothing could change the speed of a 486.  There were programs which
would run in the background and "waste" 90% of the cpu, making you
program run at 10% speed.

There are also programs that would run when the system was idle
executing 'HLT' or similar, to make the cpu power down for a bit to make
the system use less power when idle.  Linux does this by default.

> Does somebody know such a tool for linux ? Or is this on modern cpus not more 
> needed !

Modern processors can actually be slowed down unlike the old ones, and
it is done through powernow/speedstep/acpi.

> I imagine, with these tools, power would last much longer, when I can bring my 
> processor down to 100MHz.

You can't do that.  I know AMD Athlon 64's usually have 3 speeds, with
800MHz being the lowest.  I have seen 800, 1200, 2000 MHz for example.
Lower speeds also run lower voltage which further helps reduce power
use.  It does require using powernow to do it though either through
powernowd, cpufreqd, or the acpi interface to it.

> Or do I think wrong ????

I am sure of it.

Len Sorensen

Reply to: