Automated adoption of devkit-power latencies

Richard Hughes hughsient at
Tue Nov 11 07:24:40 PST 2008

On Tue, 2008-11-11 at 16:17 +0100, Phil Knirsch wrote:
> Richard Hughes wrote:
> > On Tue, 2008-11-11 at 14:53 +0100, Phil Knirsch wrote:
> >> Using monitoring information e.g. from collectd or other sources this 
> >> could automatically be detected though and then the system could be 
> >> automatically transitioned into a related power saving states depending 
> >> on the load.
> > 
> > What's doing the monitoring? Or is this policy from something like cron
> > or IPA?
> > 
> See above. Something like collectd could be used as a source for that 
> information.

Sorry, I missed that. Sure, that would work.

> >> I'd personally like to use devkit-power and it's API as a service, as 
> >> overloading it with such functionality might very quickly lead to the 
> >> problems we've seen in the past with HAL where everything was put into
> >> a single service.
> > 
> > No, I think it's 100% on topic for DK-p. Powersaving is inextricably
> > linked to latency in my opinion.
> > 
> What about cases where you want to completely shut down a device though 
> as you know it's not used?

Well, I think for the sort of latencies we are talking about (us and low
order ms) we need to do this in the kernel driver by default. The logic
goes like this: If the device isn't being used, power it down _UNLESS_
it takes more time than $CURRENT_LATENCY_SETTING to wakeup.

This way everything sleeps by default.


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