xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

powerpc/lib: optimise PPC32 memcmp

Browse Source 
At the time being, memcmp() compares two chunks of memory
byte per byte.

This patch optimises the comparison by comparing word by word.

On the same way as commit 15c2d45d17 ("powerpc: Add 64bit
optimised memcmp"), this patch moves memcmp() into a dedicated
file named memcmp_32.S

A small benchmark performed on an 8xx comparing two chuncks
of 512 bytes performed 100000 times gives:

Before : 5852274 TB ticks
After:   1488638 TB ticks

This is almost 4 times faster

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Christophe Leroy
2018-05-30 07:06:15 +00:00
committed by Michael Ellerman
parent f36bbf21e8
commit 2676b89eb8
3 changed files with 47 additions and 19 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
arch/powerpc/lib/string.S
View File

@@ -54,23 +54,6 @@ _GLOBAL(strncmp)
blr
EXPORT_SYMBOL(strncmp)
#ifdef CONFIG_PPC32
_GLOBAL(memcmp)
PPC_LCMPI 0,r5,0
beq- 2f
mtctr r5
addi r6,r3,-1
addi r4,r4,-1
1: lbzu r3,1(r6)
lbzu r0,1(r4)
subf. r3,r0,r3
bdnzt 2,1b
blr
2: li r3,0
blr
EXPORT_SYMBOL(memcmp)
#endif
_GLOBAL(memchr)
PPC_LCMPI 0,r5,0
beq- 2f