[PATCH v16 0/2] net: optimize __rte_raw_cksum

scott.k.mitch1
2026-01-23T16:03:06Z

From: Scott <scott_mitchell@apple.com>

This series optimizes __rte_raw_cksum by replacing memcpy with direct
pointer access, enabling compiler vectorization on both GCC and Clang.

Patch 1 adds __rte_may_alias to unaligned typedefs to prevent a GCC
strict-aliasing bug where struct initialization is incorrectly elided.

Patch 2 uses the improved unaligned_uint16_t type in __rte_raw_cksum
to enable compiler optimizations while maintaining correctness across
all architectures (including strict-alignment platforms).

Performance results show significant improvements (40% for small buffers,
up to 8x for larger buffers) on Intel Xeon with Clang 18.1.

Changes in v16:
- Add Fixes tag and Cc stable/author for backporting (patch 1)

Changes in v15:
- Use NOHUGE_OK and ASAN_OK constants in REGISTER_FAST_TEST

Changes in v14:
- Split into two patches: EAL typedef fix and checksum optimization
- Use unaligned_uint16_t directly instead of wrapper struct
- Added __rte_may_alias to unaligned typedefs to prevent GCC bug

Scott Mitchell (2):
eal: add __rte_may_alias to unaligned typedefs
net: __rte_raw_cksum pointers enable compiler optimizations

app/test/meson.build | 1 +
app/test/test_cksum_fuzz.c | 240 +++++++++++++++++++++++++++++++++++
app/test/test_cksum_perf.c | 2 +-
lib/eal/include/rte_common.h | 34 ++---
lib/net/rte_cksum.h | 14 +-
5 files changed, 266 insertions(+), 25 deletions(-)
create mode 100644 app/test/test_cksum_fuzz.c

--
2.39.5 (Apple Git-154)