Re: [PATCH v9 0/5] riscv: Add fine-tuned checksum functions

From: Conor Dooley
Date: Wed Nov 01 2023 - 07:50:58 EST


On Tue, Oct 31, 2023 at 05:18:50PM -0700, Charlie Jenkins wrote:
> Each architecture generally implements fine-tuned checksum functions to
> leverage the instruction set. This patch adds the main checksum
> functions that are used in networking.
>
> This patch takes heavy use of the Zbb extension using alternatives
> patching.
>
> To test this patch, enable the configs for KUNIT, then CHECKSUM_KUNIT
> and RISCV_CHECKSUM_KUNIT.
>
> I have attempted to make these functions as optimal as possible, but I
> have not ran anything on actual riscv hardware. My performance testing
> has been limited to inspecting the assembly, running the algorithms on
> x86 hardware, and running in QEMU.
>
> ip_fast_csum is a relatively small function so even though it is
> possible to read 64 bits at a time on compatible hardware, the
> bottleneck becomes the clean up and setup code so loading 32 bits at a
> time is actually faster.
>
> Relies on https://lore.kernel.org/lkml/20230920193801.3035093-1-evan@xxxxxxxxxxxx/

I coulda sworn I reported build issues against the v8 of this series
that are still present in this v9. For example:
https://patchwork.kernel.org/project/linux-riscv/patch/20231031-optimize_checksum-v9-3-ea018e69b229@xxxxxxxxxxxx/

Cheers,
Conor.

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