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Subject: RE: [PATCH v12 1/3] net: optimize __rte_raw_cksum and add tests
Date: Sat, 10 Jan 2026 15:47:04 +0100
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Thread-Topic: [PATCH v12 1/3] net: optimize __rte_raw_cksum and add tests
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From: =?iso-8859-1?Q?Morten_Br=F8rup?= <mb@smartsharesystems.com>
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Cc: <stephen@networkplumber.org>,
	"Scott" <scott_mitchell@apple.com>
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> From: Scott <scott_mitchell@apple.com>
>=20
> __rte_raw_cksum uses a loop with memcpy on each iteration.
> GCC 15+ is able to vectorize the loop but Clang 18.1 is not.
> Replacing the memcpy with unaligned_uint16_t pointer access enables
> both GCC and Clang to vectorize with SSE/AVX/AVX-512.
>=20
> This patch adds comprehensive fuzz testing and updates the performance
> test to measure the optimization impact.
>=20
> Performance results from cksum_perf_autotest on Intel Xeon
> (Cascade Lake, AVX-512) built with Clang 18.1 (TSC cycles/byte):
>=20
>   Block size    Before    After    Improvement
>          100      0.40     0.24        ~40%
>         1500      0.50     0.06        ~8x
>         9000      0.49     0.06        ~8x
>=20
> Signed-off-by: Scott Mitchell <scott.k.mitch1@gmail.com>
> ---

Probably makes no practical difference, but consider marking the =
__rte_raw_cksum() function __rte_pure:
https://elixir.bootlin.com/dpdk/v25.11/source/lib/eal/include/rte_common.=
h#L228

With or without __rte_pure marking,
Acked-by: Morten Br=F8rup <mb@smartsharesystems.com>