On Sun 2007-07-08 16:20:46, david@xxxxxxx wrote: > On Mon, 9 Jul 2007, Pavel Machek wrote: > > >>>>>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). > >> > >>instead of trying to freeze most of the system, could you do something > >>like start a virtual machine sandbox to write the data out, and not let > >>any userspace other then the sandbox operate? > >> > >>you would need to throw away disk buffers so that you don't mix current > >>pending I/O with I/O from the sandbox, and this would be a visable change > >>for how suspend is setup, but wouldn't this work? > > > >It feels kind of expensive, but yes, we could use another kernel for > >doing the dump. Kdump people are using that. We could use hypervisor > >for doing the dump. Xen people are doing that. (But I do not think any > >of those solutions is suitable for "lets hibernate my notebook" case). > > expensive and reliable beats efficiant and unrelaible. > > why do you say that neither would work for the "lets hibernate my > notebook" case? Both would work. One would eat 8-64MB of your RAM, permanently; second would eat 5-15% of your cpu, permanently. Not very suitable. Who says current solution is unreliable? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
