Re: [RFD] Automatic suspend

Rafael J. Wysocki
2009-02-16T23:26:05Z

On Monday 16 February 2009, Pavel Machek wrote:
> Hi!
>
> > The recent descussion about the Android PM patches sent by Arve shows that
> > there is a need to introduce a mechanism allowing us to:
> > (1) automatically put the system as a whole into a sleep state (eg. suspend to
> > RAM) when it is found to be "idle", where the meaning of "idle" has to be
> > defined too,
>
> Well; I'd prefer to keep the interface very minimal.
>
> If no devices are being used,

We'll need some kind of infrastructure to detect such situations.

> and next wakeup is far enough in the future,

What exactly do you mean by "next wakeup"?

> just put system to sleep. Long enough == so far away that suspend/wakeup
> is short compared to that... like 20 seconds on PC.

Well 10s will be fine on the majority of my test boxes, but that's a detail.

> Ok, it probably needs to be opt-in: echo auto-mem > /sys/power/state
> should do the trick.

Agreed.

> This will need either fixing all the applications not to poll, or
> maybe someone SIGSTOP-ing apps that are in background and poll too
> often.

Polling in general is not PM-friendly, so we'll need to deal with it somehow
at one point anyway.

Thanks,
Rafael