On 08.06.21 13:11, Michael Ellerman wrote:

David Hildenbrand [off-list ref] writes:

quoted

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

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