Re: [RFD] Automatic suspend

Rafael J. Wysocki
2009-02-27T20:55:40Z

On Friday 27 February 2009, Pavel Machek wrote:
> On Fri 2009-02-27 15:22:39, Rafael J. Wysocki wrote:
> > On Friday 27 February 2009, Pavel Machek wrote:
> > > Hi!
> > >
> > > > > > Then, the decision making logic will be able to use /sys/power/sleep whenever
> > > > > > it wishes to and the kernel will be able to refuse to suspend if it's not
> > > > > > desirable at the moment.
> > > > > >
> > > > > > It seems to be flexible enough to me.
> > > > >
> > > > > This seems flexible enough to avoid race conditions, but it forces the
> > > > > user space power manager to poll when the kernel refuse suspend.
> > > >
> > > > And if the kernel is supposed to start automatic suspend, it has to monitor
> > > > all of the wakelocks. IMO, it's better to allow the power manager to poll the
> > > > kernel if it refuses to suspend.
> > >
> > > polling is evil -- it keeps CPU wake up => wastes power.
> > >
> > > Wakelocks done right are single atomic_t... and if you set it to 0,
> > > you just unblock "sleeper" thread or something. Zero polling and very
> > > simple...
> >
> > Except that you have to check all of the wakelocks periodically in a loop =>
> > polling. So?
>
> No. I want to have single atomic_t for all the wakelocks... at least
> in non-debug version. Debug version will be slower. I believe you
> originally suggested that.

I did, but please don't call it "wakelocks". It's confusing.

Thanks,
Rafael