On Mon, Aug 07 2023 at 14:18, Peter Zijlstra wrote:
> /**
> * futex_hash - Return the hash bucket in the global hash
> * @key: Pointer to the futex key for which the hash is calculated
> @@ -114,10 +137,29 @@ late_initcall(fail_futex_debugfs);
> */
> struct futex_hash_bucket *futex_hash(union futex_key *key)
> {
> - u32 hash = jhash2((u32 *)key, offsetof(typeof(*key), both.offset) / 4,
> + u32 hash = jhash2((u32 *)key,
> + offsetof(typeof(*key), both.offset) / sizeof(u32),
> key->both.offset);
> + int node = key->both.node;
> +
> + if (node == -1) {
NUMA_NO_NODE please all over the place.
> + /*
> + * In case of !FLAGS_NUMA, use some unused hash bits to pick a
> + * node -- this ensures regular futexes are interleaved across
> + * the nodes and avoids having to allocate multiple
> + * hash-tables.
> + *
> + * NOTE: this isn't perfectly uniform, but it is fast and
> + * handles sparse node masks.
> + */
> + node = (hash >> futex_hashshift) % nr_node_ids;
> + if (!node_possible(node)) {
> + node = find_next_bit_wrap(node_possible_map.bits,
> + nr_node_ids, node);
> + }
Smart.
>
> +static inline unsigned int futex_size(unsigned int flags)
> +{
> + return 1 << (flags & FLAGS_SIZE_MASK);
> +}
> +
> static inline bool futex_flags_valid(unsigned int flags)
If you reorder these two functions in the patch which introduces them,
this diff gets readable :)
Aside of that this thing is really hard to review :)
