[ltp] CPU Idle and whine

[linux-thinkpad@linux-thinkpad.org]

on Feb 5, 2006, 20:40, Richard Neill wrote:

[ ... ]

> > 1) Setting cstate to C3 or C2. It's bad because the power is drained.
> > 2) Unloading uhci_hcd (if you don't need USB devices)
> > 3) Undervolting


I forgot to mention HZ manipulation. You may want to reduce HZ to 250 or 
100, and see if it helps (regardless of the kernel).


> 1) I tried removing the processor and thermal modules. This does fix the 
> problem. What am I losing by doing this?


Locking your CPU to the maximum power state? (C1, I presume) Or, perhaps, 
handling over the CPU state switching to BIOS (if any). This is just as 
good/bad as locking cstate to a certain value.

Why would you need to remove thermal module?


> 2)Alternatively, I looked at /proc/acpi/processor/CPU/power and the 
> machine switches between C1 when idle and C2 when busy. It never reaches 
> C3, and no other levels are listed.


The governor you are using is probably responsible. Or BIOS, if you let 
it. But do you hear whining at cstates C2 and C1?


> Changing the value of /sys/module/processor/parameters/max_cstate has no 
> effect.


I am curious as to your BIOS settings on performance.

Undervolting solved (among other things) the whining problem for my T43, 
so I stopped exploring other options.





ivr
-- 
The only "intuitive" interface is the nipple. After that, it's all learned.
(Bruce Ediger, bediger@teal.csn.org, in comp.os.linux.misc, on X interfaces.)