Re: [PATCH bpf-next v2] bpf: Speed up htab lookups for u32/u64 keys

["Alexei Starovoitov" <alexei.starovoitov@gmail.com>]

On Mon, Sep 21, 2026 at 02:28 PM Mykyta Yatsenko <mykyta.yatsenko5@gmail.com> wrote:
> +	/*
> +	 * Fold the jhash constant and key length into hashrnd once for the
> +	 * fixed-size fast paths instead of doing it on every lookup.
> +	 */
> +	if (htab->map.key_size == sizeof(u32) ||
> +	    htab->map.key_size == sizeof(u64))
> +		htab->hashrnd += JHASH_INITVAL + htab->map.key_size;

This optimization is probably not needed anymore?

> -static void *__htab_map_lookup_elem(struct bpf_map *map, void *key)
> +static __always_inline void *__htab_lookup(struct bpf_map *map, void *key, u32 key_size)

__htab_lookup() is __always_inline, but htab_map_hash() and
lookup_nulls_elem_raw() that consume key_size are not.
Whether memcmp() becomes a single compare in _u32/_u64 variants
is up to the compiler. Make both __always_inline?