Re: [Dynamicpower-devel] DPM review

[Livio T. <liv...@en...>]

Hello, Matthew!
Thanks a lot for your help!

I would have some questions too.
You sed me that " the dpm_set_os function which is placed in the idle 
loop and scheduler by default": but does the standard implementation 
(the standard code) exploit operating states different from "idle" and 
"task"? In other words: in my montavista kernel I have 13 states: relock 
idle-task idle sleep task-4 task-3 task-2 task-1 task task+1 task+2 
task+3 task+4. Are these states exploited by the linux standard kernel 
or new dpm_set_os calls are needed to use all these states? If new calls 
are needed: which states are used by default?
When you say that it is necessary to "and add dpm_set_os in the right 
place to trigger the transition": do you mean in an external program 
(e.g. in a dpm manager), into the applications code (if I am not wrong 
these applications are labeled ad power-aware into the documentation I 
read) or directly in the kernel code?
Do you know whether a power manager implementation (to manage the 
policies) does exist?

Thanks a lot for your help and for your useful hints!!!!
Livius

Matthew Locke wrote:

> As Todd mentioned, there are a lot of details and the only 
> documentation is the stuff you've seen.   Here is a quick summary 
> starting from the top:
>
> Policies are a mapping of operating points to operating states.
> Linux changes the operating state using the dpm_set_os function which 
> is placed in the idle loop and scheduler by default.
> When the operating state is changed, dpm will switch to the operating 
> point that is mapped to that operating state.
> It is expected that people will define additional operating states and 
> add dpm_set_os in the right place to trigger the transition.
> Device constraints are not mandatory.
>
> Note;  I left out classes for simplicity.  They may or may not be 
> necessary depending your device.
>
> On Aug 17, 2005, at 2:39 AM, Livio Tenze wrote:
>
>> Hi all!
>>
>> I am new in the DPM field. I would like to find a good document to 
>> learn the DPM functionalities? May you suggest me?
>> I read some articles and part of montavista documentation, but some 
>> subjects are not clear: in particular I do not understand how the DPM 
>> changes the operationg point. I am working on a freescale MX21 
>> processor: I set the operating point, the operating classes and the 
>> policies. When I enable a policy, how does the system change the 
>> operating state? According to which rule?
>> Is it mandatory to set the the device constraints?
>>
>> Thanks to all!
>> Livius
>>
>>
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