Messages in this thread | | | Date | Wed, 13 Jun 2001 15:49:51 +0200 (CEST) | From | Dave Jones <> | Subject | Re: Changing CPU Speed while running Linux |
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On Wed, 13 Jun 2001, Magnus Sandberg wrote:
> I have a brand new Dell Inspiron 8000, laptop. It can run in 700 MHz or > 850 MHz. The manual says that the machine/BIOS switches speed dependent on > CPU load. I have not installed Linux yet, but it works with Win2000.
Intel Speedstep iirc. My Vaio also has it. My findings so far:
On mains it runs at 700MHz, whilst on batteries it drops to ~550MHz. If I boot an ACPI enabled kernel, the speed changes according to CPU load, but with a smaller window. I've seen it go as low as 50MHz, but only up to a maximum of 200MHz. The fact that it only has a maximum of 200MHz in this mode probably explains the need for the no-idle switch in the current ACPI implementation.
As there are no public documents on Speedstep, it's not clear to me whether this is a limitation of Speedstep, or the ACPI implementation. Judging by the fact that Windows seems to run at full speed, I'd be inclined to think the latter.
regards,
Dave.
-- | Dave Jones. http://www.suse.de/~davej | SuSE Labs
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