Re: New NUMA scheduler and hotplug CPU

["Martin J. Bligh" <mbligh@aracnet.com>]

> Well lets not worry too much about this for now. We could use
> static arrays and cpu_possible for now until we get a feel
> for what specific architectures want.
> 
> To be honest I haven't seen the hotplug CPU code and I don't
> know about what architectures want to be doing with it, so
> this is my preferred direction just out of ignorance.
> 
> An easy next step toward a dynamic scheme would be just to
> re-init the entire sched domain topology (the generic init uses
> the generic NUMA topology info which will have to be handled
> by these architectures anyway). Modulo a small locking problem.
> 
> There aren't any fundamental design issues (with sched domains)
> that I can see preventing a more dynamic system so we can keep
> that in mind.

Yeah, I talked it over with Rusty some on IRC. I have more of a feeling
why he's trying to do it that way now. However, one other thought occurs
to me ... it'd be good to use the same infrastructure (sched domains)
for the workload management stuff as well (where the domains would be
defined from userspace). That'd also necessitate them being dynamic,
if you think that'd work out as a usage model.

The cpu_possible stuff might work for a first cut at hotplug I guess.
I still think it's ugly though ;-)

M.