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From: Ben Dooks <ben.dooks@codethink.co.uk>
To: Matteo Croce <mcroce@linux.microsoft.com>,
	linux-kernel@vger.kernel.org, Nick Kossifidis <mick@ics.forth.gr>,
	Guo Ren <guoren@kernel.org>,
	Christoph Hellwig <hch@infradead.org>,
	David Laight <David.Laight@aculab.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Emil Renner Berthing <kernel@esmil.dk>,
	Drew Fustini <drew@beagleboard.org>
Cc: linux-arch@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	linux-riscv@lists.infradead.org
Subject: Re: [PATCH v2 1/3] lib/string: optimized memcpy
Date: Fri, 2 Jul 2021 15:37:19 +0100	[thread overview]
Message-ID: <0e0fa030-8995-b930-5e22-954349a0b82e@codethink.co.uk> (raw)
In-Reply-To: <20210702123153.14093-2-mcroce@linux.microsoft.com>

On 02/07/2021 13:31, Matteo Croce wrote:
> From: Matteo Croce <mcroce@microsoft.com>
> 
> Rewrite the generic memcpy() to copy a word at time, without generating
> unaligned accesses.
> 
> The procedure is made of three steps:
> First copy data one byte at time until the destination buffer is aligned
> to a long boundary.
> Then copy the data one long at time shifting the current and the next long
> to compose a long at every cycle.
> Finally, copy the remainder one byte at time.
> 
> This is the improvement on RISC-V:
> 
> original aligned:	 75 Mb/s
> original unaligned:	 75 Mb/s
> new aligned:		114 Mb/s
> new unaligned:		107 Mb/s
> 
> and this the binary size increase according to bloat-o-meter:
> 
> Function     old     new   delta
> memcpy        36     324    +288
> 
> 
> Signed-off-by: Matteo Croce <mcroce@microsoft.com>
> ---
>   lib/string.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++--
>   1 file changed, 77 insertions(+), 3 deletions(-)

Doesn't arch/riscv/lib/memcpy.S also exist for an architecture
optimised version? I would have thought the lib/string.c version
was not being used?


-- 
Ben Dooks				http://www.codethink.co.uk/
Senior Engineer				Codethink - Providing Genius

https://www.codethink.co.uk/privacy.html

  reply	other threads:[~2021-07-02 14:58 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-02 12:31 [PATCH v2 0/3] lib/string: optimized mem* functions Matteo Croce
2021-07-02 12:31 ` [PATCH v2 1/3] lib/string: optimized memcpy Matteo Croce
2021-07-02 14:37   ` Ben Dooks [this message]
2021-07-02 14:44     ` Matteo Croce
2021-07-02 12:31 ` [PATCH v2 2/3] lib/string: optimized memmove Matteo Croce
2021-07-02 12:31 ` [PATCH v2 3/3] lib/string: optimized memset Matteo Croce
2021-07-10 21:31 ` [PATCH v2 0/3] lib/string: optimized mem* functions Andrew Morton
2021-07-10 23:07   ` Matteo Croce
2021-07-12  8:15     ` David Laight

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