My CPU is stuck in C0 state all the time

[risidoro]

Hi all,
i'm having a problem with ubuntu gutsy (actually i don't know if i had the same problem in feisty, i did not check at the time): my CPU (athlon xp 2800+) runs very hot, about 60C while in Win it always stays at 45C.

After googling around quite some time i realized it could be a acpi related problem so i checked /proc/acpi/processor/CPU0/ files and found something wrong in there.


isidoro@neo:~$ cat /proc/acpi/processor/CPU0/info
processor id: 0
acpi id: 0
bus mastering control: no
power management: no
throttling control: no
limit interface: no


and


isidoro@neo:~$ cat /proc/acpi/processor/CPU0/power
active state: C0
max_cstate: C8
bus master activity: 00000000
maximum allowed latency: 4353 usec
states:


In the first output it says "Power Management: NO" i don't know if it is correct or not but it seesm strange.
The second output is what troubles me more: it says that the active state is C0 and, moreover, "States:" field is empty! This means that my CPU stays all the time in C0 (max power) mode while it should automatically switch to c1 and c2 states (i think that c3 state is not supported).

This is a great problem for me 'cos, even if i have a desktop pc, running it at full cpu power all the time will shorten my cpu life and waste a lot of energy.

What can i do? Do you think i have to file a bug report?
Thanks!


PS: some details: i'm running gutsy beta 1, my pc is a desktop with athlon xp 2800+ (no powernow or cpu throttling capabilities) and an asus a7v600-x mobo.

[MaX]

Hmm.. I have this aswell on my AMD X2 4200+
On my last processor it wen't down to 50% capacity when used moderately.

[risidoro]

It seems i've solved my problem by installing athcool package. Now my cpu stays at the incledibly low 26°C!!!

proc/acpi/processor/CPU0/power still reports "Active state: C0" and has a empty "States" field so it seems linux is not yet recognising any power state in my CPU (i'm starting to wonder whether my athlon xp does actually support C1,C2,C3 states after all).

Anyway, if you have an old athlon xp/sempron (socket a) and and old motherboard chipset (kt600 in my case) then you should try the athcool package. Be careful though! This package can have indesiserable effects like: distorted audio (not in my case), slower hdd performances (i've yet to try, i've still to find a good benchmark program) or even, in rare cases, data loss!!!

EDIT:

More info on athlon CPU's here: http://www.daniel.nofftz.net/linux/Athlon-Powersaving-HOWTO.html