Re: understanding acpi

Rodney Cacy
2006-12-05T11:11:20Z

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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>>
>>
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>

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