Messages in this thread | | | Date | Wed, 24 Jan 2001 20:43:19 -0500 (EST) | From | Ari Heitner <> | Subject | Re: SpeedStep,MHz,BogoMIPS,timing.. |
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On Wed, 24 Jan 2001, Robert Dale wrote:
> > I bought a laptop which uses an Intel CPU with SpeedStep. Sometimes when > I boot the kernel recognizes the full MHz, and other times it is much less. > And of course the BogoMIPS reflect this we well. > > I'm wondering if this has any sort of side-effect on the kernel? Will > it disrupt timing loops and such? (I have no idea what I'm talking about ;)
My tp 600X has speedstep as well. When running on ac, the CPU goes full speed (500MHz). On battery, it goes 1/4 speed (133Mhz) to save juice (must work, i can run for 7 hours or so with an extra battery in the ultrabay).
linux seems happy with the switch -- the timing loops are close to right (they're supposed to be order-of-magnitude). obviously if you boot the thing then plug it in, the exact MHz count in /proc/cpuinfo will be wrong. But it's never seemed a big idea.
You can get the same effect on an old 386 or 486 which still has a "Turbo" switch.
> > Since Linus works at Transmeta, the kings of power saving, I'm guessing this > has no effect. >
Quite the opposite :) SpeedStep is Intel's rather pathetic answer to Crusoe's continuously variable powersaving (it's like having a two-speed car in comparison to a slick continously variable transmission like Honda has been working on iirc).
I love my 600X, and it blazes on wall power. But it took me 30 minutes t compile the 8k lines Python-Visual today in class running on battery (g++ 2.95 with the optimizer on ... painful) :)
ari
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