Re: Hibernation Redesign

Rafael J. Wysocki
2007-07-11T22:27:05Z

On Thursday, 12 July 2007 00:17, Al Boldi wrote:
> Mark Lord wrote:
> > Jeremy Maitin-Shepard wrote:
> > > I'll certainly admit the kexec idea is vaporware currently,
>
> Your idea is starting to become a reality with this thread:
> "[PATCH 0/2] Kexec jump: The first step to kexec base hibernation"
>
> > > but it does
> > > differ in a significant way from freezer-based approaches, such that I
> > > don't think it should be referred to as just another implementation of a
> > > freezer. Specifically, it doesn't require that the "old kernel" be in a
> > > "consistent" state to a greater extent than suspend to ram; it is the
> > > case that all of the devices must be quiesced or shut down to some
> > > extent, but doing this without races and deadlocks (and without the
> > > freezer) is certainly very, very similar to what needs to be done for
> > > suspend to ram, which will need to be solved anyway. Unlike the
> > > existing hibernate approaches, however, it will not be necessary to use
> > > any of the driver infrastructure once switched to the "save image"
> > > kernel, and thus it will not matter what locks are held, for instance.
> >
> > I really doubt that kexec(a special kernel) is going to solve anything
> > here. The new kernel will have to initialize, probe for devices, etc.
> > Which will take time.
> > Which will slow down hibernate to an unacceptable degree.
> > Right now, it (TuxOnIce) is *very* fast.
> > Adding 10 seconds or so for reprobing/resetting/reiniting devices
> > is not going to be useful.
> > And modifying all of the drivers to *not* do their usual probe sequence
> > sounds rather intrusive and is likely also a non-starter here.
> >
> > Or is it?
>
> Well, it's definitely less intrusive than readying drivers for the freezer.

There's nothing like this!

Greetings,
Rafael

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