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From: Matteo Croce <mcroce@linux.microsoft.com>
To: linux-riscv@lists.infradead.org
Cc: linux-kernel@vger.kernel.org, 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>,
	Guo Ren <guoren@kernel.org>, Christoph Hellwig <hch@lst.de>
Subject: [PATCH v4 0/3] riscv: optimized mem* functions
Date: Sun, 19 Sep 2021 21:21:01 +0200	[thread overview]
Message-ID: <20210919192104.98592-1-mcroce@linux.microsoft.com> (raw)

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.

A further improvement could be to use multiple read and writes as the
assembly version was trying to do.

Tested on a BeagleV Starlight with a SiFive U74 core, where the
improvement is noticeable.

v3 -> v4:
- incorporate changes from proposed generic version:
  https://lore.kernel.org/lkml/20210617152754.17960-1-mcroce@linux.microsoft.com/

v2 -> v3:
- alias mem* to __mem* and not viceversa
- use __alias instead of a tail call

v1 -> v2:
- reduce the threshold from 64 to 16 bytes
- fix KASAN build
- optimize memset

Matteo Croce (3):
  riscv: optimized memcpy
  riscv: optimized memmove
  riscv: optimized memset

 arch/riscv/include/asm/string.h |  18 ++--
 arch/riscv/kernel/Makefile      |   1 -
 arch/riscv/kernel/riscv_ksyms.c |  17 ----
 arch/riscv/lib/Makefile         |   4 +-
 arch/riscv/lib/memcpy.S         | 108 ----------------------
 arch/riscv/lib/memmove.S        |  64 -------------
 arch/riscv/lib/memset.S         | 113 -----------------------
 arch/riscv/lib/string.c         | 154 ++++++++++++++++++++++++++++++++
 8 files changed, 164 insertions(+), 315 deletions(-)
 delete mode 100644 arch/riscv/kernel/riscv_ksyms.c
 delete mode 100644 arch/riscv/lib/memcpy.S
 delete mode 100644 arch/riscv/lib/memmove.S
 delete mode 100644 arch/riscv/lib/memset.S
 create mode 100644 arch/riscv/lib/string.c

-- 
2.31.1


             reply	other threads:[~2021-09-19 19:21 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-19 19:21 Matteo Croce [this message]
2021-09-19 19:21 ` [PATCH v4 1/3] riscv: optimized memcpy Matteo Croce
2021-09-19 19:21 ` [PATCH v4 2/3] riscv: optimized memmove Matteo Croce
2021-09-19 22:05   ` kernel test robot
2021-09-27 10:48     ` Matteo Croce
2021-09-29 17:04       ` Emil Renner Berthing
2021-09-19 19:21 ` [PATCH v4 3/3] riscv: optimized memset Matteo Croce
2021-09-19 22:00 ` [PATCH v4 0/3] riscv: optimized mem* functions Matteo Croce
2021-10-08  1:26 ` Palmer Dabbelt
2021-10-08  1:39   ` Matteo Croce

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