On Mon, Feb 25, 2019 at 11:24 PM Dave Hansen <dave.hansen@xxxxxxxxx> wrote:
>
> 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*.
I had thought separating [3/6] and [4/6] can ease the review. And I
will merge them in next version.
Thanks and regards,
Pingfan
