Re: [PATCH 08/22] mm/vmstat: Avoid on each online CPU loops

On Tue 29-11-16 15:08:10, Thomas Gleixner wrote:

On Mon, 28 Nov 2016, Michal Hocko wrote:

quoted

On Sun 27-11-16 00:13:36, Sebastian Andrzej Siewior wrote:
[...]

quoted

 static void __init init_cpu_node_state(void)
 {
-	int cpu;
+	int node;
 
-	for_each_online_cpu(cpu)
-		node_set_state(cpu_to_node(cpu), N_CPU);
+	for_each_online_node(node)
+		node_set_state(node, N_CPU);

Is this really correct? The point of the original code was to mark only
those nodes which have at least one CPU. Or am I missing something?

You're right. An online node does not necessarily have an online CPU.

	for_each_online_node(node) {
		if (cpumask_weight(cpumask_of_node(node)) > 0)
			node_set_state(node, N_CPU);
	}

is probably more correct.

Yes, this looks correct. Considering that the same cpumask_weight is
used in another function I guess a small helper would be nice. E.g.
bool node_has_cpus(int node)
{
	return cpumask_weight(cpumask_of_node(node)) > 0;
}

-- 
Michal Hocko
SUSE Labs

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>