Re: [PATCH v1 05/12] mm/memory_hotplug: remove nid parameter from remove_memory() and friends

[David Hildenbrand]

On 08.06.21 13:11, Michael Ellerman wrote:
> David Hildenbrand <david@xxxxxxxxxx> writes:
> > There is only a single user remaining. We can simply try to offline all
> > online nodes - which is fast, because we usually span pages and can skip
> > such nodes right away.
>
> That makes me slightly nervous, because our big powerpc boxes tend to
> trip on these scaling issues before others.
>
> But the spanned pages check is just:
>
> void try_offline_node(int nid)
> {
> 	pg_data_t *pgdat = NODE_DATA(nid);
>          ...
> 	if (pgdat->node_spanned_pages)
> 		return;
>
> So I guess that's pretty cheap, and it's only O(nodes), which should
> never get that big.

Exactly. And if it does turn out to be a problem, we can walk all memory 
blocks before removing them, collecting the nid(s).

--
Thanks,

David / dhildenb