linux-kernel - [PATCH v4 0/8] Multibyte memset variations

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Message-Id: <20170720184539.31609-1-willy@infradead.org>
Date:   Thu, 20 Jul 2017 11:45:31 -0700
From:   Matthew Wilcox <willy@...radead.org>
To:     linux-kernel@...r.kernel.org
Cc:     minchan@...nel.org, Matthew Wilcox <mawilcox@...rosoft.com>,
        akpm@...uxfoundation.org, mpe@...erman.id.au
Subject: [PATCH v4 0/8] Multibyte memset variations

From: Matthew Wilcox <mawilcox@...rosoft.com>

A relatively common idiom we're missing is a function to fill an area
of memory with a pattern which is larger than a single byte.  I first
noticed this with a zram patch which wanted to fill a page with an
'unsigned long' value.  There turn out to be quite a few places in
the kernel which can benefit from using an optimised function rather
than a loop; sometimes text size, sometimes speed, and sometimes both.
The optimised PowerPC version (not included here) improves performance
by about 30% on POWER8 on just the raw memset_l().

Most of the extra lines of code come from the three testcases I added.

Matthew Wilcox (8):
  Add multibyte memset functions
  Add testcases for memset16/32/64
  x86: Implement memset16, memset32 & memset64
  ARM: Implement memset32 & memset64
  alpha: Add support for memset16
  zram: Convert to using memset_l
  sym53c8xx_2: Convert to use memset32
  vga: Optimise console scrolling

 arch/alpha/include/asm/string.h     |  15 +--
 arch/alpha/include/asm/vga.h        |   2 +-
 arch/alpha/lib/memset.S             |  10 +-
 arch/arm/include/asm/string.h       |  14 +++
 arch/arm/kernel/armksyms.c          |   2 +
 arch/arm/lib/memset.S               |  24 +++--
 arch/mips/include/asm/vga.h         |   7 ++
 arch/powerpc/include/asm/vga.h      |   8 ++
 arch/sparc/include/asm/vga.h        |  25 +++++
 arch/x86/include/asm/string_32.h    |  24 +++++
 arch/x86/include/asm/string_64.h    |  36 +++++++
 drivers/block/zram/zram_drv.c       |  13 +--
 drivers/scsi/sym53c8xx_2/sym_hipd.c |  11 +-
 include/linux/string.h              |  30 ++++++
 include/linux/vt_buffer.h           |  12 +++
 lib/Kconfig                         |   3 +
 lib/string.c                        | 196 ++++++++++++++++++++++++++++++++++++
 17 files changed, 394 insertions(+), 38 deletions(-)

-- 
2.13.2