RE: AMD's PowerNow?
----Original Message-----
From: Derek Broughton [mailto:derek_broughton@hotmail.com]
Sent: Tuesday, January 29, 2002 12:28 PM
To: debian-laptop@lists.debian.org
Subject: Re: AMD's PowerNow?
From: "Alan Shutko" <ats@acm.org>
> Derek Broughton <derek_broughton@hotmail.com> writes:
>
> > As I understand it, speed-step is not supported because it's a typical
> > kludge for Windows. Linux doesn't need it because it idles when not
busy
> > instead of using busy loops.
>
> No, Speedstep is not supported because Intel won't release
> documentation on it (specifically, how to know when it's turned on or
> off so the kernel can adjust timing loops). It _does_ give a power
> benefit when used on my machine.
>I have a real problem buying into that explanation. Why would Intel create
>Speed-step cpus and then not let you know how to use it? It's no benefit
to
>Intel unless Microsoft specifically paid them to add the functionality and
>keep it exclusive to them. But Microsoft couldn't care less about energy
>saving. Seems way too much like a conspiracy theory for me.
>As for power benefits on your machine, my understanding is that the kernel
>idles when it can but some applications can still keep the cpu busy.
>Obviously you'll save power over a limited period of time if you slow down
>the machine - but where's the benefit? It makes the application run
longer,
>and your battery will probably still run out at the same point in your
>processing - just after a longer elapsed time.
>
>derek
Actually I think they added that into their mobile processors to keep
Transmeta
from taking market share from their mobile processor line. The Crusoe
processor
as far as I know was the first one to actually slow the cpu clock down
depending
what program was being run. It's not just slowing it down when their is idle
time.
Do you really need a processor running at 1Mhz. to run a text editing tool?
No
but you would need that speed to play a DVD. The faster the processor speed
the
more power it uses. So if you slow down or speed up depending on the work
load
you should see a difference in power usage.
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