Re: [PATCH 0/2] arm64: csum: Add fused copy and Internet checksum

[saeed bishara]

On Sun, Nov 1, 2026 at 3:34 PM Demian Shulhan <demyansh@xxxxxxxxx> wrote:
>
> I would prefer to keep only the scalar version of the fused copy+csum.
> It reads the data once instead of twice, and on real Armv9 hardware it
> cuts end-to-end cycles/byte for bulk TCP over WireGuard by 3-12%
> depending on the core (+6-8% throughput). It uses only general-purpose
> registers, so there is no FPSIMD state to save and it is safe in any
> context.
>
> If you are OK with the scalar path, I can send v2 with NEON dropped,
> the scalar path only, and the KUnit fix for the x86 zero-length case
> Jakub reported.
>
The scalar path seems like generic C code and not restricted to arm64,
curious how that performs against existing (e.g. x86) assembly
optimized implementation.
saeed