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Date:   Wed, 1 Nov 2023 11:50:46 +0000
From:   Conor Dooley <conor@kernel.org>
To:     Charlie Jenkins <charlie@rivosinc.com>
Cc:     Palmer Dabbelt <palmer@dabbelt.com>,
        Samuel Holland <samuel.holland@sifive.com>,
        David Laight <David.Laight@aculab.com>,
        Xiao Wang <xiao.w.wang@intel.com>,
        Evan Green <evan@rivosinc.com>,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-arch@vger.kernel.org,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Arnd Bergmann <arnd@arndb.de>,
        Conor Dooley <conor.dooley@microchip.com>
Subject: Re: [PATCH v9 0/5] riscv: Add fine-tuned checksum functions
Message-ID: <20231101-palace-tightly-97a1d35a4597@spud>
References: <20231031-optimize_checksum-v9-0-ea018e69b229@rivosinc.com>
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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.
>=20
> This patch takes heavy use of the Zbb extension using alternatives
> patching.
>=20
> To test this patch, enable the configs for KUNIT, then CHECKSUM_KUNIT
> and RISCV_CHECKSUM_KUNIT.
>=20
> 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.
>=20
> 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.
>=20
> Relies on https://lore.kernel.org/lkml/20230920193801.3035093-1-evan@rivo=
sinc.com/

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_ch=
ecksum-v9-3-ea018e69b229@rivosinc.com/

Cheers,
Conor.

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