Re: [RFD] Automatic suspend

Rafael J. Wysocki
2009-02-20T22:44:18Z

On Friday 20 February 2009, Oliver Neukum wrote:
> Am Freitag 20 Februar 2009 11:46:55 schrieb Rafael J. Wysocki:
> > On Thursday 19 February 2009, Oliver Neukum wrote:
> > > Am Donnerstag 19 Februar 2009 23:21:46 schrieb Rafael J. Wysocki:
> > > > > That's the whole point behind userspace wakelocks! They provide a
> > > > > mechanism for userspace to tell the kernel when (as far as userspace
> > >
> > > is
> > >
> > > > > concerned) it is or is not okay to auto-sleep.
> > > >
> > > > Still, one can go further and observe that the user space can in fact
> > > > start automatic suspend by itself whenever it knows it's appropriate
> > > > ...
> > >
> > > User space initiating this is a race condition.
> >
> > Do you mean a race with the other user space processes or with the kernel?
>
> With the set of runnable processes.There's always a window between
> evaluating the current set of runnable tasks and telling the kernel to sleep.
> IMO the most elegant solution would be a task attribute that would signal
> the kernel that a task should not count as keeping the system busy even
> if it is runnable and trigger the sleep in kernel space.

Please see my last reply to Arve (http://lkml.org/lkml/2009/2/20/182) and tell
me what you think.

Best,
Rafael