lkml.org 
[lkml]   [2001]   [Jun]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Changing CPU Speed while running Linux
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

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 12:55    [from the cache]
©2003-2011 Jasper Spaans