Re: So, what's the status on the recent patches here?

David Singleton
2006-09-09T00:39:52Z

On 9/3/06, Pavel Machek <pavel@ucw.cz> wrote:
> > >That depends on the definition, but I think of suspend states as the ones
> > >that require processes to be frozen before they can be entered. IMHO it is
> > >quite clear that such states cannot be handled in the same way as those
> > >that do not require the freezing of processes, so they are not the same.
> >
> > You are correct, processes do need to be frozen before a suspend.
> > That's the prepare to suspend part of the suspend process, and
> > the transtition is the suspending and finish is the un-freezing
> > of the processes to resume execution.
> >
> > And those same steps are the same steps required to transition the
> > system to a new operating point, whether it's suspend or change
> > from 1.4GHz to 600MHz.
>
> No, processes are not frozen for simple cpu frequency change -- on
> non-broken cpus.

I didn't say cpu frequency changes freeze processes. I said a suspend
does a prepare to suspend step (which freezes processes) and a cpu frequency
change does a prepare to change frequency step (where it will run the driver
notifier list to get drivers set to scale).

They both do the same three steps:

1) prepare to transition

2) transition

3) finish transition

That's one of my arguements as to why suspend states should be treated
just like frequency states.

David

> Pavel
> --
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
>