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

[Davidlohr Bueso]

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.