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From:   Guo Ren <guoren@kernel.org>
Date:   Tue, 22 Jun 2021 10:39:48 +0800
Message-ID: <CAJF2gTTipWCvwu0p7CdPqr2krfHvviQxqdNPCy9VHBUXvh6FyQ@mail.gmail.com>
Subject: Re: [PATCH v3 0/3] riscv: optimized mem* functions
To:     Nick Kossifidis <mick@ics.forth.gr>
Cc:     Matteo Croce <mcroce@linux.microsoft.com>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Atish Patra <atish.patra@wdc.com>,
        Emil Renner Berthing <kernel@esmil.dk>,
        Akira Tsukamoto <akira.tsukamoto@gmail.com>,
        Drew Fustini <drew@beagleboard.org>,
        Bin Meng <bmeng.cn@gmail.com>,
        David Laight <David.Laight@aculab.com>
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On Tue, Jun 22, 2021 at 9:09 AM Nick Kossifidis <mick@ics.forth.gr> wrote:
>
> Hello Matteo,
>
> =CE=A3=CF=84=CE=B9=CF=82 2021-06-17 18:27, Matteo Croce =CE=AD=CE=B3=CF=
=81=CE=B1=CF=88=CE=B5:
> > From: Matteo Croce <mcroce@microsoft.com>
> >
> > Replace the assembly mem{cpy,move,set} with C equivalent.
> >
> > Try to access RAM with the largest bit width possible, but without
> > doing unaligned accesses.
> >
> > Tested on a BeagleV Starlight with a SiFive U74 core, where the
> > improvement is noticeable.
> >
>
> There are already generic C implementations for memcpy/memmove/memset at
> https://elixir.bootlin.com/linux/v5.13-rc7/source/lib/string.c#L871 but
> are doing one byte at a time, I suggest you update them to do
> word-by-word copy instead of introducing yet another memcpy/memmove C
> implementation on arch/riscv/.
Yes, I've tried to copy the Glibc version into arch/csky/abiv1, and
Arnd suggested putting them into generic.
ref: https://lore.kernel.org/linux-arch/20190629053641.3iBfk9-I_D29cDp9yJnI=
dIg7oMtHNZlDmhLQPTumhEc@z/#t

>
>
>


--
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/