From: "Morten Brørup" <mb@smartsharesystems.com>
To: <scott.k.mitch1@gmail.com>, <dev@dpdk.org>
Cc: <stephen@networkplumber.org>, "Scott" <scott_mitchell@apple.com>
Subject: RE: [PATCH v12 1/3] net: optimize __rte_raw_cksum and add tests
Date: Sat, 10 Jan 2026 15:47:04 +0100 [thread overview]
Message-ID: <98CBD80474FA8B44BF855DF32C47DC35F65646@smartserver.smartshare.dk> (raw)
In-Reply-To: <20260110015651.26201-2-scott.k.mitch1@gmail.com>
> From: Scott <scott_mitchell@apple.com>
>
> __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.
>
> This patch adds comprehensive fuzz testing and updates the performance
> test to measure the optimization impact.
>
> Performance results from cksum_perf_autotest on Intel Xeon
> (Cascade Lake, AVX-512) built with Clang 18.1 (TSC cycles/byte):
>
> Block size Before After Improvement
> 100 0.40 0.24 ~40%
> 1500 0.50 0.06 ~8x
> 9000 0.49 0.06 ~8x
>
> 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 Brørup <mb@smartsharesystems.com>
next prev parent reply other threads:[~2026-01-10 14:47 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-10 1:56 [PATCH v12 0/3] net: optimize raw checksum computation scott.k.mitch1
2026-01-10 1:56 ` [PATCH v12 1/3] net: optimize __rte_raw_cksum and add tests scott.k.mitch1
2026-01-10 2:28 ` Scott Mitchell
2026-01-10 14:47 ` Morten Brørup [this message]
2026-01-10 1:56 ` [PATCH v12 2/3] eal: add workaround for UBSAN alignment false positive scott.k.mitch1
2026-01-10 15:02 ` Morten Brørup
2026-01-10 1:56 ` [PATCH v12 3/3] eal/net: add workaround for GCC optimization bug scott.k.mitch1
2026-01-10 15:29 ` Morten Brørup
2026-01-11 6:21 ` Scott Mitchell
2026-01-10 16:59 ` [PATCH v12 0/3] net: optimize raw checksum computation Stephen Hemminger
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