Re: Attempted summary of suspend-blockers LKML thread

Paul E. McKenney
2010-08-04T20:51:59Z

On Wed, Aug 04, 2010 at 10:42:08PM +0200, Pavel Machek wrote:
> Hi!
>
> > > If this doesn't work for the Android folks for whatever reason, another
> > > approach would be to do the freeze in user code, which could track
> > > whether any user-level resources (pthread mutexes, SysV semas, whatever)
> > > where held, and do the freeze on a thread-by-thread basis within each
> > > "victim" application as the threads reach safe points.
> >
> > The main problem I see with the cgroups solution is that it doesn't seem
> > to do anything to handle avoiding loss of wakeup events.
>
> In different message, Arve said they are actually using low-power idle
> to emulate suspend on Android.

Hello, Pavel,

Could you please point me at this message?

Thanx, Paul

> This came like a bit of a shock to me ("why do they make it so complex
> then"), but... it also means that as soon as you are able to stop
> "unwanted" processing, you can just leave normal cpuidle mechanisms to
> deal with the rest...
>
> (Of course, you'll also have to fix kernel timers not to beat
> unneccessarily often; still that's better solution that just stoping
> them all and then sprinkling wakelocks all over the kernel to deal
> with obvious bugs it introduces...)
> Pavel
> --
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html