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Date:   Tue, 31 Oct 2023 07:57:19 +0000
From:   Conor Dooley <conor.dooley@microchip.com>
To:     Charlie Jenkins <charlie@rivosinc.com>
CC:     Palmer Dabbelt <palmer@dabbelt.com>,
        Conor Dooley <conor@kernel.org>,
        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>
Subject: Re: [PATCH v8 0/5] riscv: Add fine-tuned checksum functions
Message-ID: <20231031-shrouded-simmering-e60d23d17fa3@wendy>
References: <20231027-optimize_checksum-v8-0-feb7101d128d@rivosinc.com>
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On Fri, Oct 27, 2023 at 03:43:50PM -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/

Not sure if the dep here is related, but the series is back to failing
to build properly. Patch 3's build is broken everywhere pretty much, and
patch 4's allmodconfigs don't build:

https://patchwork.kernel.org/project/linux-riscv/list/?series=3D797256

Cheers,
Conor.

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