Re: [linux-pm] Re: Hibernation considerations

Rafael J. Wysocki
2007-07-23T13:53:40Z

On Monday, 23 July 2007 15:08, Miklos Szeredi wrote:
> > > > The reason is that we want them to "park" in safe places, ie. where there
> > > > are no locks held etc.  Thus, these safe places need to be chosen somehow
> > > > and since they are not marked throughout the code, we choose the obvious
> > > > one. :-)
> > >
> > > Why shouldn't locks be held?
> > >
> > > No locks which are required for suspend must be held, sure.  But
> > > otherwise holding locks doesn't matter at all.
> >
> > If you can provide a way to tell them apart, this would work.
>
> Without some marking we can't tell obviously.
>
> Are there many such locks? We can easily check by adding some
> debugging code to the lock primitives, to make them yell if they are
> used during suspend.

This way we can only obtain information from systems that use hibernation
quite often.

Alan has recently proposed to introduce "suspend locks" to be acquired during
a suspend/hibernation and such that we can leave uninterruptible tasks that
don't hold any of them.

Unfortunately, I have no link to his original message at hand.

Greetings,
Rafael

--
"Premature optimization is the root of all evil." - Donald Knuth