Re: [PATCH 2/6] futex: Implement FUTEX2_NUMA

Davidlohr Bueso
2024-10-25T18:33:27Z

On Fri, 25 Oct 2024, Peter Zijlstra wrote:\n

> static int __init futex_init(void)
> {
>- unsigned int futex_shift;
>- unsigned long i;
>+ unsigned int order, n;
>+ unsigned long size, i;
>
> #ifdef CONFIG_BASE_SMALL
> futex_hashsize = 16;
> #else
>- futex_hashsize = roundup_pow_of_two(256 * num_possible_cpus());
>+ futex_hashsize = 256 * num_possible_cpus();
>+ futex_hashsize /= num_possible_nodes();
>+ futex_hashsize = roundup_pow_of_two(futex_hashsize);
> #endif
>+ futex_hashshift = ilog2(futex_hashsize);
>+ size = sizeof(struct futex_hash_bucket) * futex_hashsize;
>+ order = get_order(size);
>+
>+ for_each_node(n) {

Probably want to skip nodes that don't have CPUs, those will never
have the remote for .node value.