AMD cpu slows down (I think)

Saturday, 30 October 2004

I'm trying to find info on my laptop problem but can't find anything really 
explanatory. I assume it's something to do with CPU speed auto-setting on 
battery power and your site seems to be relevant.

My situation: I have a Compaq Presario 2197CA, AMD Athlon XP-M 2800+ CPU. With 
Fedora Core 1, no problems on AC or battery power. After upgrade to FC2 with 
kernel-2.6.5-1.358, originally no problem (I don't recall). But at some point 
I updated the kernel to kernel-2.6.8-1.521 and possibly then, possibly 
because of some other "upgrade" my computer slips into a different mode when 
on battery power.

In this "mode" it becomes extremely, irritatingly slow to use. A command shell 
takes visible time to scroll/update. GUI windows take maddening seconds to 
draw, etc.

Research leads me to believe that this is a "feature" of the Powernowstuff or 
something, but it is definitely not a feature I want.

A found a web site 
(http://www.codemonkey.org.uk/projects/cpufreq/powernow-k7.shtml) that says:

"This meant that until version 2.6.6 of the kernel, Powernow was non 
functional on these laptops."
and 
"Compaq Presario 2100. 	Has 14 PST tables. None of which match the cpuid of 
the processor (0x7A0)"

I conclude that this means that my original FC1 and FC2 kernels (pre-2.6.6) 
would have had disfunctional support for Powernow but that my new kernel has 
"fixed" support for this. And this, I assume, is the source of my problem.

However, I can find no docs about how to control Powernow or, better yet, turn 
it off (I use my laptop at school and home and I rarely use battery power so 
it's not an issue for me).

After my long ramble, 4 questions:

1. am I correct in my assessment of the situation, do you think?
2. how could anybody want to use a system that is struggling to update windows 
and such, no matter how much longer it made their batteries last?
3. is my problem more likely the result of poor/nonexistent graphics 
acceleration which causes the CPU to do graphics work as well as system work, 
thus when the CPU is slowed down, graphics slow down?
4. how can I turn this damn Powernow thing off?

Thanks in advance.
-- 
Trevor Smith // trevor(a)haligonian.com