On Mon, 21 May 2012 10:25:21 +0200 (CEST), Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote: > On Mon, 21 May 2012, Rusty Russell wrote: > > > On Fri, 20 Apr 2012 16:18:04 +0200 (CEST), Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote: > > > On Fri, 20 Apr 2012, Srivatsa S. Bhat wrote: > > > The whole notifier business needs a redesign as well, because we don't > > > have a way to express proper dependencies, we add random notifier > > > points and the teardown path is ass backwards. The whole thing wants > > > to be a tree which can be walked in either direction and from any > > > point. Right now we cut the trunk first and keep the single limb up > > > with a helicopter and start dismantling it. > > > > But there are two ways to do it. One is to eliminate the need for > > callbacks. The other is to make a full dependency-based callback > > What do you mean with fully eliminating the need for callbacks. Do you > want to put the necessary bringup/shutdown function calls just in the > core code so we get rid of the notifiers or do you have something > different in mind ? Eliminate is probably too hard, but with park/unpark I can see it getting less common. Maybe few enough that we can simplify. > > Not sure whether calling notifiers in parallel is going to be a big win: > > they'll end up fighting over the cpu we're taking down. But I could be > > wrong. > > I'm not going to aim for parallel in the first place. That was just an > idea and if we chose the right implementation then parallelism can be > added later. Parallel CPUs going offline/online is probably a bigger win. Both for suspend/resume and powersaving. > > The original concept of stopping the machine for cpu hotplug and trying > > not to effect any other kernel code has jumped the shark: I think we > > need to look seriously at a complete rewrite where we don't use > > stop_machine. > > Yep. Working on it. :) I thought you might be :) I'd love to review once you've got something. Cheers, Rusty. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
