hibernation/snapshot design [was Re: [PATCH] Remove process freezer from suspend to RAM pathway]

Pavel Machek
2007-07-08T22:13:33Z

Hi!

> > Actaully, I'm perfectly fine with that, as long as each task blocked by the
> > driver due to suspend has PF_FROZEN (or something similar) set. Then, at
> > least theoretically, we'll be able to drop the freezer from the suspend code
> > path and move it after device_suspend() (or the hibernation-specific
> > equivalent) for hibernation (in that case there shouldn't be a problem with
> > any task waiting on I/O while the freezer is running ;-)).
>
> I don't see the need for a freezer for snapshot but that's a different
> issue. (stop_machine looks good enough to me).

Freezer is not needed for snapshot -- it is needed so that we can
write out the snapshot to disk without the need for special
drivers/block/simple-ide-for-suspend.c. (We are doing snapshot, then
write to disk from userland code in uswsusp).
Pavel

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