Re: [RFD] Automatic suspend

Oliver Neukum
2009-02-20T23:20:43Z

Am Samstag 21 Februar 2009 00:11:28 schrieb Arve Hjønnevåg:
> On Fri, Feb 20, 2009 at 2:05 PM, Oliver Neukum <oliver@neukum.org> wrote:
> > Am Freitag 20 Februar 2009 11:46:55 schrieb Rafael J. Wysocki:
> >> On Thursday 19 February 2009, Oliver Neukum wrote:

> > 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.
>
> It is not always safe to enter suspend when no tasks are runnable. For
> instance, a key event could be on a user space queue, but the code
> that reads from that queue has been paged out.

In that case you'd have a task waiting for IO. The driver should refuse
to suspend or wake up the system as IO is completed. It may be
inefficient to suspend for such a presumably short time, but it is not
a correctness issue.

Regards
Oliver