mirror of
https://github.com/torvalds/linux.git
synced 2024-11-06 03:51:48 +00:00
17968fbbd1
I noticed __clear_user high up in a profile of one of my RAID stress tests. The testcase was doing a dd from /dev/zero which ends up calling __clear_user. __clear_user is basically a loop with a single 4 byte store which is horribly slow. We can do much better by aligning the desination and doing 32 bytes of 8 byte stores in a loop. The following testcase was used to verify the patch: http://ozlabs.org/~anton/junkcode/stress_clear_user.c To show the improvement in performance I ran a dd from /dev/zero to /dev/null on a POWER7 box: Before: # dd if=/dev/zero of=/dev/null bs=1M count=10000 10485760000 bytes (10 GB) copied, 3.72379 s, 2.8 GB/s After: # time dd if=/dev/zero of=/dev/null bs=1M count=10000 10485760000 bytes (10 GB) copied, 0.728318 s, 14.4 GB/s Over 5x faster. Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
165 lines
2.5 KiB
ArmAsm
165 lines
2.5 KiB
ArmAsm
/*
|
|
* String handling functions for PowerPC.
|
|
*
|
|
* Copyright (C) 1996 Paul Mackerras.
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* as published by the Free Software Foundation; either version
|
|
* 2 of the License, or (at your option) any later version.
|
|
*/
|
|
#include <asm/processor.h>
|
|
#include <asm/errno.h>
|
|
#include <asm/ppc_asm.h>
|
|
|
|
.section __ex_table,"a"
|
|
PPC_LONG_ALIGN
|
|
.text
|
|
|
|
_GLOBAL(strcpy)
|
|
addi r5,r3,-1
|
|
addi r4,r4,-1
|
|
1: lbzu r0,1(r4)
|
|
cmpwi 0,r0,0
|
|
stbu r0,1(r5)
|
|
bne 1b
|
|
blr
|
|
|
|
/* This clears out any unused part of the destination buffer,
|
|
just as the libc version does. -- paulus */
|
|
_GLOBAL(strncpy)
|
|
PPC_LCMPI 0,r5,0
|
|
beqlr
|
|
mtctr r5
|
|
addi r6,r3,-1
|
|
addi r4,r4,-1
|
|
1: lbzu r0,1(r4)
|
|
cmpwi 0,r0,0
|
|
stbu r0,1(r6)
|
|
bdnzf 2,1b /* dec ctr, branch if ctr != 0 && !cr0.eq */
|
|
bnelr /* if we didn't hit a null char, we're done */
|
|
mfctr r5
|
|
PPC_LCMPI 0,r5,0 /* any space left in destination buffer? */
|
|
beqlr /* we know r0 == 0 here */
|
|
2: stbu r0,1(r6) /* clear it out if so */
|
|
bdnz 2b
|
|
blr
|
|
|
|
_GLOBAL(strcat)
|
|
addi r5,r3,-1
|
|
addi r4,r4,-1
|
|
1: lbzu r0,1(r5)
|
|
cmpwi 0,r0,0
|
|
bne 1b
|
|
addi r5,r5,-1
|
|
1: lbzu r0,1(r4)
|
|
cmpwi 0,r0,0
|
|
stbu r0,1(r5)
|
|
bne 1b
|
|
blr
|
|
|
|
_GLOBAL(strcmp)
|
|
addi r5,r3,-1
|
|
addi r4,r4,-1
|
|
1: lbzu r3,1(r5)
|
|
cmpwi 1,r3,0
|
|
lbzu r0,1(r4)
|
|
subf. r3,r0,r3
|
|
beqlr 1
|
|
beq 1b
|
|
blr
|
|
|
|
_GLOBAL(strncmp)
|
|
PPC_LCMPI 0,r5,0
|
|
beq- 2f
|
|
mtctr r5
|
|
addi r5,r3,-1
|
|
addi r4,r4,-1
|
|
1: lbzu r3,1(r5)
|
|
cmpwi 1,r3,0
|
|
lbzu r0,1(r4)
|
|
subf. r3,r0,r3
|
|
beqlr 1
|
|
bdnzt eq,1b
|
|
blr
|
|
2: li r3,0
|
|
blr
|
|
|
|
_GLOBAL(strlen)
|
|
addi r4,r3,-1
|
|
1: lbzu r0,1(r4)
|
|
cmpwi 0,r0,0
|
|
bne 1b
|
|
subf r3,r3,r4
|
|
blr
|
|
|
|
_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
|
|
|
|
_GLOBAL(memchr)
|
|
PPC_LCMPI 0,r5,0
|
|
beq- 2f
|
|
mtctr r5
|
|
addi r3,r3,-1
|
|
1: lbzu r0,1(r3)
|
|
cmpw 0,r0,r4
|
|
bdnzf 2,1b
|
|
beqlr
|
|
2: li r3,0
|
|
blr
|
|
|
|
#ifdef CONFIG_PPC32
|
|
_GLOBAL(__clear_user)
|
|
addi r6,r3,-4
|
|
li r3,0
|
|
li r5,0
|
|
cmplwi 0,r4,4
|
|
blt 7f
|
|
/* clear a single word */
|
|
11: stwu r5,4(r6)
|
|
beqlr
|
|
/* clear word sized chunks */
|
|
andi. r0,r6,3
|
|
add r4,r0,r4
|
|
subf r6,r0,r6
|
|
srwi r0,r4,2
|
|
andi. r4,r4,3
|
|
mtctr r0
|
|
bdz 7f
|
|
1: stwu r5,4(r6)
|
|
bdnz 1b
|
|
/* clear byte sized chunks */
|
|
7: cmpwi 0,r4,0
|
|
beqlr
|
|
mtctr r4
|
|
addi r6,r6,3
|
|
8: stbu r5,1(r6)
|
|
bdnz 8b
|
|
blr
|
|
90: mr r3,r4
|
|
blr
|
|
91: mfctr r3
|
|
slwi r3,r3,2
|
|
add r3,r3,r4
|
|
blr
|
|
92: mfctr r3
|
|
blr
|
|
|
|
.section __ex_table,"a"
|
|
PPC_LONG 11b,90b
|
|
PPC_LONG 1b,91b
|
|
PPC_LONG 8b,92b
|
|
.text
|
|
#endif
|