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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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63e6c5b810
A number of our chips like loads and stores to be paired. A small kernel
module testcase shows the improvement of pairing loads and stores in
copy_4k_page:
POWER6: +9%
POWER7: +1.5%
#include <linux/module.h>
#include <linux/mm.h>
#define ITERATIONS 10000000
static int __init copypage_init(void)
{
struct timespec before, after;
unsigned long i;
struct page *destpage, *srcpage;
char *dest, *src;
destpage = alloc_page(GFP_KERNEL);
srcpage = alloc_page(GFP_KERNEL);
dest = page_address(destpage);
src = page_address(srcpage);
getnstimeofday(&before);
for (i = 0; i < ITERATIONS; i++)
copy_4K_page(dest, src);
getnstimeofday(&after);
free_page((unsigned long)dest);
free_page((unsigned long)src);
printk(KERN_DEBUG "copy_4K_page loop took %lu ns\n",
(after.tv_sec - before.tv_sec) * NSEC_PER_SEC +
(after.tv_nsec - before.tv_nsec));
return 0;
}
static void __exit copypage_exit(void)
{
}
module_init(copypage_init)
module_exit(copypage_exit)
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Anton Blanchard");
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
108 lines
2.0 KiB
ArmAsm
108 lines
2.0 KiB
ArmAsm
/*
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* Copyright (C) 2008 Mark Nelson, IBM Corp.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <asm/processor.h>
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#include <asm/ppc_asm.h>
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#include <asm/asm-offsets.h>
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.section ".toc","aw"
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PPC64_CACHES:
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.tc ppc64_caches[TC],ppc64_caches
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.section ".text"
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_GLOBAL(copy_4K_page)
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li r5,4096 /* 4K page size */
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BEGIN_FTR_SECTION
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ld r10,PPC64_CACHES@toc(r2)
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lwz r11,DCACHEL1LOGLINESIZE(r10) /* log2 of cache line size */
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lwz r12,DCACHEL1LINESIZE(r10) /* get cache line size */
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li r9,0
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srd r8,r5,r11
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mtctr r8
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.Lsetup:
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dcbt r9,r4
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dcbz r9,r3
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add r9,r9,r12
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bdnz .Lsetup
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END_FTR_SECTION_IFSET(CPU_FTR_CP_USE_DCBTZ)
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addi r3,r3,-8
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srdi r8,r5,7 /* page is copied in 128 byte strides */
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addi r8,r8,-1 /* one stride copied outside loop */
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mtctr r8
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ld r5,0(r4)
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ld r6,8(r4)
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ld r7,16(r4)
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ldu r8,24(r4)
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1: std r5,8(r3)
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std r6,16(r3)
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ld r9,8(r4)
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ld r10,16(r4)
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std r7,24(r3)
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std r8,32(r3)
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ld r11,24(r4)
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ld r12,32(r4)
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std r9,40(r3)
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std r10,48(r3)
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ld r5,40(r4)
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ld r6,48(r4)
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std r11,56(r3)
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std r12,64(r3)
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ld r7,56(r4)
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ld r8,64(r4)
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std r5,72(r3)
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std r6,80(r3)
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ld r9,72(r4)
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ld r10,80(r4)
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std r7,88(r3)
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std r8,96(r3)
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ld r11,88(r4)
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ld r12,96(r4)
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std r9,104(r3)
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std r10,112(r3)
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ld r5,104(r4)
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ld r6,112(r4)
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std r11,120(r3)
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stdu r12,128(r3)
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ld r7,120(r4)
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ldu r8,128(r4)
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bdnz 1b
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std r5,8(r3)
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std r6,16(r3)
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ld r9,8(r4)
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ld r10,16(r4)
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std r7,24(r3)
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std r8,32(r3)
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ld r11,24(r4)
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ld r12,32(r4)
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std r9,40(r3)
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std r10,48(r3)
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ld r5,40(r4)
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ld r6,48(r4)
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std r11,56(r3)
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std r12,64(r3)
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ld r7,56(r4)
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ld r8,64(r4)
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std r5,72(r3)
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std r6,80(r3)
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ld r9,72(r4)
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ld r10,80(r4)
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std r7,88(r3)
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std r8,96(r3)
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ld r11,88(r4)
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ld r12,96(r4)
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std r9,104(r3)
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std r10,112(r3)
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std r11,120(r3)
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std r12,128(r3)
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blr
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