Power Management

[Jordan Crouse]

On 08/06/07 16:49 +0100, Richard Hughes wrote:
> On Fri, 2007-06-08 at 11:42 -0400, Chris Ball wrote:
> > Hi,
> > 
> >    > Is there a mechanism for either applications or users to change the
> >    > parameters? And what constitutes "idle"?
> > 
> > A first shot at what constitues "idle" is if all of the below are true:
> > 
> >    * if the CPU isn't under load
> 
> Which we can get from the system load, or is there a better geode
> specific way of doing this?

No - you have to get this from the system load.

> >    * if the video on the screen isn't changing
> 
> How can we get this from userspace?

You can't, really - the X server is the only one with that knowledge,
and he'll be the one turning on and off the DCON automatically without
your consent.  Sorry.. :(

> >    * if we aren't dealing with any keypresses/input from the user
> 
> We can monitor input devices...
> 
> >    * if the currently running activity hasn't told sugar/OHM to inhibit
> >      sleeping while it's running
> 
> Like when?
> 
> >    * if there isn't a software tick (dynticks/tickless) planned for the
> >      very near future
> 
> Can we get this info from the kernel?

Probably not - and if you could, the latency to tell you would probably
be longer then the delay.  This will also have to be automatically triggered.
But keep in mind - this sort of behavior is way out there - we're still
struggling with simple policy based sleeps at this point.

Jordan

-- 
Jordan Crouse
Senior Linux Engineer
Advanced Micro Devices, Inc.
<www.amd.com/embeddedprocessors>