Re: [PATCH 3/6] sched_ext: Introduce per-node idle cpumasks

[Andrea Righi]

On Wed, Dec 18, 2024 at 06:10:17AM -1000, Tejun Heo wrote:
> Hello,
> 
> On Wed, Dec 18, 2024 at 11:21:30AM +0100, Andrea Righi wrote:
> ...
> > > Are node IDs guaranteed to be consecutive? Shouldn't it be `node >=
> > > nr_node_ids`? Also, should probably add node_possible(node)?
> > 
> > Or even better add node_online(node), an offline NUMA node shouldn't be
> > used in this context.
> 
> That can be too but then we'd have to worry about synchronizing against
> going on/offline. Looks like that's protected by mem_hotplug_lock, so we'd
> have to require get_online_mems() around these iterations, which might not
> be worth it. Besides, if we want to triger abort on incorrect input, we'd
> have to call sched_ext ops under mem_hotplug_lock, which we probably can't
> do.

We can probably ignore this for now and add a "restart" logic like we do
with CPU hotplugging at some point.

-Andrea