linux/arch/powerpc/lib/copypage_64.S
Anton Blanchard fde69282b7 powerpc: POWER7 optimised copy_page using VMX and enhanced prefetch
Implement a POWER7 optimised copy_page using VMX and enhanced
prefetch instructions. We use enhanced prefetch hints to prefetch
both the load and store side. We copy a cacheline at a time and
fall back to regular loads and stores if we are unable to use VMX
(eg we are in an interrupt).

The following microbenchmark was used to assess the impact of
the patch:

http://ozlabs.org/~anton/junkcode/page_fault_file.c

We test MAP_PRIVATE page faults across a 1GB file, 100 times:

# time ./page_fault_file -p -l 1G -i 100

Before: 22.25s
After:  18.89s

17% faster

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2012-07-03 14:14:44 +10:00

112 lines
2.1 KiB
ArmAsm

/*
* Copyright (C) 2008 Mark Nelson, IBM Corp.
*
* 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/page.h>
#include <asm/processor.h>
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>
.section ".toc","aw"
PPC64_CACHES:
.tc ppc64_caches[TC],ppc64_caches
.section ".text"
_GLOBAL(copy_page)
BEGIN_FTR_SECTION
lis r5,PAGE_SIZE@h
FTR_SECTION_ELSE
b .copypage_power7
ALT_FTR_SECTION_END_IFCLR(CPU_FTR_VMX_COPY)
ori r5,r5,PAGE_SIZE@l
BEGIN_FTR_SECTION
ld r10,PPC64_CACHES@toc(r2)
lwz r11,DCACHEL1LOGLINESIZE(r10) /* log2 of cache line size */
lwz r12,DCACHEL1LINESIZE(r10) /* get cache line size */
li r9,0
srd r8,r5,r11
mtctr r8
.Lsetup:
dcbt r9,r4
dcbz r9,r3
add r9,r9,r12
bdnz .Lsetup
END_FTR_SECTION_IFSET(CPU_FTR_CP_USE_DCBTZ)
addi r3,r3,-8
srdi r8,r5,7 /* page is copied in 128 byte strides */
addi r8,r8,-1 /* one stride copied outside loop */
mtctr r8
ld r5,0(r4)
ld r6,8(r4)
ld r7,16(r4)
ldu r8,24(r4)
1: std r5,8(r3)
std r6,16(r3)
ld r9,8(r4)
ld r10,16(r4)
std r7,24(r3)
std r8,32(r3)
ld r11,24(r4)
ld r12,32(r4)
std r9,40(r3)
std r10,48(r3)
ld r5,40(r4)
ld r6,48(r4)
std r11,56(r3)
std r12,64(r3)
ld r7,56(r4)
ld r8,64(r4)
std r5,72(r3)
std r6,80(r3)
ld r9,72(r4)
ld r10,80(r4)
std r7,88(r3)
std r8,96(r3)
ld r11,88(r4)
ld r12,96(r4)
std r9,104(r3)
std r10,112(r3)
ld r5,104(r4)
ld r6,112(r4)
std r11,120(r3)
stdu r12,128(r3)
ld r7,120(r4)
ldu r8,128(r4)
bdnz 1b
std r5,8(r3)
std r6,16(r3)
ld r9,8(r4)
ld r10,16(r4)
std r7,24(r3)
std r8,32(r3)
ld r11,24(r4)
ld r12,32(r4)
std r9,40(r3)
std r10,48(r3)
ld r5,40(r4)
ld r6,48(r4)
std r11,56(r3)
std r12,64(r3)
ld r7,56(r4)
ld r8,64(r4)
std r5,72(r3)
std r6,80(r3)
ld r9,72(r4)
ld r10,80(r4)
std r7,88(r3)
std r8,96(r3)
ld r11,88(r4)
ld r12,96(r4)
std r9,104(r3)
std r10,112(r3)
std r11,120(r3)
std r12,128(r3)
blr