[PATCH 0/6] arm64:lib: the optimized string library routines for armv8 processors

[zhichang.yuan at linaro.org]

From: "zhichang.yuan" <zhichang.yuan at linaro.org>

In current aarch64 kernel,there are a few string library routines
implemented in arm64/lib,such as memcpy,memset, memmove,strchr.
Most string routines frequently used are provided by the
architecture-independent string library.Those routines are not efficient.

This patch focus on improving the sting routines' performance in ARMv8.
It contains eight optimized functions.The work is based on the cortex-string
project in Linaro toolchain.

The cortex-string code can be found in this website:
	https://code.launchpad.net/cortex-strings
To obtain better performance,several ideas were utilized:
1) memory burst access;
	For the long memory data operation,adopted the armv8 instruction pairs,
	ldp/stp,to transfer the bulk data.Try best to use continuous ldp/stp
	to trigger the burst access.
2) parallel processing
	The current string routines mostly processed per-byte. This patch
	processes the data in parallel.Such as strlen, it will process
	eight string bytes each time.
3) aligned memory access
	Classfy the process into several categories according to the input
	memory address parameters.For the non-alignment memory address,firstly
	process the begginning short-length data to make the memory address
	aligned,then start the remain processing on alignment address.

After the optimization,those routines have better performance than the current ones.
Please refer to this website to get the test results:
	https://wiki.linaro.org/WorkingGroups/Kernel/ARMv8/cortex-strings

--

zhichang.yuan (6):
  arm64: lib: Implement optimized memcpy routine
  arm64: lib: Implement optimized memmove routine
  arm64: lib: Implement optimized memset routine
  arm64: lib: Implement optimized memcmp routine
  arm64: lib: Implement optimized string compare routines
  arm64: lib: Implement optimized string length routines

 arch/arm64/include/asm/string.h |   15 ++
 arch/arm64/kernel/arm64ksyms.c  |    5 +
 arch/arm64/lib/Makefile         |    5 +-
 arch/arm64/lib/memcmp.S         |  258 +++++++++++++++++++++++++++++
 arch/arm64/lib/memcpy.S         |  182 ++++++++++++++++++---
 arch/arm64/lib/memmove.S        |  195 ++++++++++++++++++----
 arch/arm64/lib/memset.S         |  227 +++++++++++++++++++++++---
 arch/arm64/lib/strcmp.S         |  256 +++++++++++++++++++++++++++++
 arch/arm64/lib/strlen.S         |  131 +++++++++++++++
 arch/arm64/lib/strncmp.S        |  340 +++++++++++++++++++++++++++++++++++++++
 arch/arm64/lib/strnlen.S        |  179 +++++++++++++++++++++
 11 files changed, 1714 insertions(+), 79 deletions(-)
 create mode 100644 arch/arm64/lib/memcmp.S
 create mode 100644 arch/arm64/lib/strcmp.S
 create mode 100644 arch/arm64/lib/strlen.S
 create mode 100644 arch/arm64/lib/strncmp.S
 create mode 100644 arch/arm64/lib/strnlen.S

-- 
1.7.9.5