Re: understanding acpi

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You try to break rules and it is not easy so I do not expect that there is another mailing list where you find an easy answer for your question. In my opinion the acpid is not the right way. It is only for catching acpi events and then run scripts. Using it you can be informed that the processor changes state from c3->c2 and then you can react for the information by running an application but there is no one which revert the change (it is to force the processor to change state from c2->c3) because the kernel is only the one that can do that. It is a question for me why the battery presence allows the c3 state whilst without it only c2 is possible. I do not know, really. I think that the simplest way to deal with the noise reduction could by thermal management. Why? I guess the working fan generate the noisy sound :) so let turn it be on less frequently. Forgot about the "c" states - it is to difficult. For thermal management is an easy interface in /proc/acpi/thermal_zone. Read about it in the http://www.columbia.edu/~ariel/acpi/acpi_howto.txt, section 8. If it is too difficult to understand ask about it in other forum (maybe LinuxQuestions.org) and read, read, read...

Cheers

Oliver Henriot wrote:
Hi,

Rodney Cacy a écrit :

I'm not an expert but you can pass a boot kernel option:

processor.max_cstate

Yes, I'd actually tried setting processor.max_cstate=4 a while ago to see if this changed anything and indeed, instead of reading
max_cstate : C8
from /proc/acpi/processor/CPU0/power as I usually get, I got
max_cstate : C4
Obivious, and no good either, unfortunately. I still ran at C2 on mains and C3 on battery. I suspect my settings in /etc/acpi are not good and I'm looking for a fine manual I could rtfm in order to understand what I should doo to fine tune acpi on my machine. Where I'm stuck is to find the fine manual which I'll actually understand (I may not be very smart... ;-) ) and manage to put into application.

More inforamtion in http://www.columbia.edu/~ariel/acpi/acpi_howto.txt, section 7.

Yes, I'm actually trying to understand sections 6.3 through 6.6 of that same document, which I suspect are precisely what I'm looking for and also point at /etc/acpi. My relatively limited skills are preventing me from getting any further at the moment, but I am confident I will eventually make something of it.

Write me about the results. Now I'm working under suspending sound,lan etc. to save battery but soon I will work with the noise reduction.

Cacy


Cheers,

P.S. considering the level of other discussions on this list, I suspect I have pointed my questions to the wrong place. Question : is there a noob oriented discussion list for acpi? Anyway, sorry for the list pollution with such "low level" questions.



Oliver Henriot wrote:

Hi all list subscribers,

I'm looking for info on how acpi functions in order to get it to work the best possible on my computer. It's a Sony laptop (vaio vgn-sz3xp/c, core2duo) running Debian Etch. In particular, I'm looking for ways to reduce thermal dissipation from the CPU as much as possible, in order to queep the machine as quiet as possible. From the various docs I've read, so far I seem to understand that C-states is the way to go, throttling being probably not very efficient.

When I'm running on batteries, C3 state is active (as shown by cat /prc/acpi/processor/CPU0/power) and is the main state, whereas when I'm running on mains, C3 disappears and only C1 and C2 remain.

My question are : wouldn't it be better if I could use C3 even when on mains. Wouldn't it be even better with C4? As suggested by "Why My Cx Power State Is Not Used" I tried unloading various modules (e.g. those concerning usb but I got stuck with usbcore which refused to unload despite nothing usb being connected) without any success. Being relatively new to GNU/Linux, I'm a bit stuck here and don't know where to look or what to make of this.

Any help would be gladly welcome.

Cheers,

Oliver
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