Re: Searching Tool for CPU stepping down
On Thu, Jul 27, 2006 at 07:14:00PM +0200, Hans-J. Ullrich wrote:
> 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.
>
> Does somebody know such a tool for linux ? Or is this on modern cpus not more
> needed !
You just described cpufreq. Just use a kernel with cpufreq support and
use the "ondemand" or "conservative" governor to let the CPU switch to
various frequencies.
Note that you can't decrease the clock frequency on a 486 without
extensive hardware support on the motherboard. Some 486 notebooks had
such hardware (my old Digital notebook, for example), but the
programming interface was non-standard: the Digital tools certainly
didn't work on Compaq notebooks.
> I imagine, with these tools, power would last much longer, when I can bring my
> processor down to 100MHz.
>
> Or do I think wrong ????
Yes and no. Subtle detail: you don't want to save power, you want to
save *energy*. See my OLS 2002 CPUfreq paper:
http://www.lartmaker.nl/projects/scaling/cpufreq.ps.gz
Erik
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+-- Erik Mouw -- www.harddisk-recovery.com -- +31 70 370 12 90 --
| Lab address: Delftechpark 26, 2628 XH, Delft, The Netherlands
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