Re: Merging the Suspend2 freezer implementation.

[Nigel Cunningham <ncunningham@linuxmail.org>]

Hi.

On Wed, 2005-02-09 at 09:32, Pavel Machek wrote:
> Hi!
> 
> > > > The main change involves the introduction of a new SYNCTHREAD flag. We
> > > > use this to avoid deadlocking over processes that are running sys_sync
> > > > and siblings. Processes that enter those routines get the flag added,
> > > > and it's removed when they exit the sync routine. We then freeze in four
> > > > stages: 
> > > 
> > > Is SYNCTHREAD neccessary for me, too, or is it needed for suspend2, only?
> > 
> > It's necessary for reliable freezing under I/O load. Signalling the
> > non-sync threads first removes the race involved in some threads
> > submitting I/O while others are trying to sync. Try doing a dd and a
> > sync at the same time. The sync can take ages to return, worst case,
> > sometimes not until the dd is completed. (Actually, try doing anything
> > while a dd is running :>)
> 
> Okay, just attach this explanation when you are merging it otherwise
> I'll surely ask again...

Okay.

> > > > Finally I'd like to merge the support for freezer flags on workqueues.
> > 
> > No comment here? :>
> 
> :-). I forgot why it was neccessary, but I was too shy to ask
> ;-). Just attach nice explanation when you attempt to merge it.

Okay.

Thanks!

Nigel
-- 
Nigel Cunningham
Software Engineer, Canberra, Australia
http://www.cyclades.com

Ph: +61 (2) 6292 8028      Mob: +61 (417) 100 574