RE: [PATCH 2/2] [RFC] net: introduce fast ethernet address comparison function

Morten Brørup
2026-01-30T14:03:09Z

> From: Morten Brørup [mailto:mb@smartsharesystems.com]
> Sent: Friday, 30 January 2026 11.46
>
> Added a fast ethernet address comparison function for 64-bit CPU
> architectures without strict alignment requirements, loading the
> ethernet
> addresses as 64-bit words and comparing the relevant 6 bytes.

Some quick testing in a real application shows this is ~2 cycles faster than the standard rte_is_same_ether_addr() implementation (without the patch 1/2 changes).

>
> Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
> ---
> lib/net/rte_ether.h | 46 +++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 46 insertions(+)
>
> diff --git a/lib/net/rte_ether.h b/lib/net/rte_ether.h
> index 5552d3c1f6..1b640d81c2 100644
> --- a/lib/net/rte_ether.h
> +++ b/lib/net/rte_ether.h
> @@ -114,6 +114,52 @@ static inline int rte_is_same_ether_addr(const
> struct rte_ether_addr *ea1,
> #endif
> }
>
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this API may change, or be removed, without prior
> notice
> + *
> + * Check if two Ethernet addresses are the same, performance
> optimized.
> + *
> + * @warning
> + * Intentional buffer overrun:
> + * The Ethernet addresses are loaded as 64-bit integers, i.e.
> + * two bytes past the memory holding the Ethernet addresses are
> loaded.
> + * The caller must ensure that this does not cause problems.
> + * If an Ethernet address 'ea' is a field in a structure 'S', it can
> be verified as follows:
> + * \code{.c}
> + * static_assert(sizeof(struct S) >= offsetof(struct S, ea) +
> sizeof(uint64_t));
> + * \endcode
> + *
> + * @param ea1
> + * A pointer to the first ether_addr structure containing the
> Ethernet address.
> + * @param ea2
> + * A pointer to the second ether_addr structure containing the
> Ethernet address.
> + *
> + * @return
> + * - true if the given two Ethernet addresses are the same;
> + * - false otherwise.
> + */
> +__rte_experimental
> +__rte_pure
> +static inline bool
> +rte_is_same_ether_addr_fast(const struct rte_ether_addr *ea1,
> + const struct rte_ether_addr *ea2)
> +{
> +#if defined(RTE_ARCH_64) && !defined(RTE_ARCH_STRICT_ALIGN)
> + const unaligned_uint64_t * const a1 = (const unaligned_uint64_t
> *)ea1;
> + const unaligned_uint64_t * const a2 = (const unaligned_uint64_t
> *)ea2;
> +#if RTE_BYTE_ORDER == RTE_BIG_ENDIAN
> + return (*a1 ^ *a2) >> 16 == 0;
> +#elif RTE_BYTE_ORDER == RTE_LITTLE_ENDIAN
> + return (*a1 ^ *a2) << 16 == 0;
> +#else
> +#error "Unknown byte order."
> +#endif /* RTE_BYTE_ORDER */
> +#else
> + return rte_is_same_ether_addr(ea1, ea2);
> +#endif
> +}
> +
> /**
> * Check if an Ethernet address is filled with zeros.
> *
> --
> 2.43.0