On 2/24/19 4:34 AM, Pingfan Liu wrote:
> +#ifdef CONFIG_NUMA
> /*
> * There are unfortunately some poorly designed mainboards around that
> * only connect memory to a single CPU. This breaks the 1:1 cpu->node
> @@ -618,6 +619,9 @@ static void __init numa_init_array(void)
> rr = next_node_in(rr, node_online_map);
> }
> }
> +#else
> +static void __init numa_init_array(void) {}
> +#endif
What functional effect does this #ifdef have?
Let's look at the code:
> static void __init numa_init_array(void)
> {
> int rr, i;
>
> rr = first_node(node_online_map);
> for (i = 0; i < nr_cpu_ids; i++) {
> if (early_cpu_to_node(i) != NUMA_NO_NODE)
> continue;
> numa_set_node(i, rr);
> rr = next_node_in(rr, node_online_map);
> }
> }
and "play compiler" for a bit.
The first iteration will see early_cpu_to_node(i)==1 because:
static inline int early_cpu_to_node(int cpu)
{
return 0;
}
if CONFIG_NUMA=n.
In other words, I'm not sure this patch does *anything*.
