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28f2ce2772
In commit 863d775c48, kunpeng920 is added to default memcpy version,
however, there is performance degradation when the copy size is some large bytes, eg: 100k.
This is the result, tested in glibc-2.28:
before backport after backport Performance improvement
memcpy_1k 0.005 0.005 0.00%
memcpy_10k 0.032 0.029 10.34%
memcpy_100k 0.356 0.429 -17.02%
memcpy_1m 7.470 11.153 -33.02%
This is the demo
#include "stdio.h"
#include "string.h"
#include "stdlib.h"
char a[1024*1024] = {12};
char b[1024*1024] = {13};
int main(int argc, char *argv[])
{
int i = atoi(argv[1]);
int j;
int size = atoi(argv[2]);
for (j = 0; j < i; j++)
memcpy(b, a, size*1024);
return 0;
}
# gcc -g -O0 memcpy.c -o memcpy
# time taskset -c 10 ./memcpy 100000 1024
Co-authored-by: liqingqing <liqingqing3@huawei.com>
52 lines
1.9 KiB
C
52 lines
1.9 KiB
C
/* Multiple versions of memcpy. AARCH64 version.
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Copyright (C) 2017-2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/* Define multiple versions only for the definition in libc. */
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#if IS_IN (libc)
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/* Redefine memcpy so that the compiler won't complain about the type
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mismatch with the IFUNC selector in strong_alias, below. */
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# undef memcpy
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# define memcpy __redirect_memcpy
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# include <string.h>
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# include <init-arch.h>
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extern __typeof (__redirect_memcpy) __libc_memcpy;
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extern __typeof (__redirect_memcpy) __memcpy_generic attribute_hidden;
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extern __typeof (__redirect_memcpy) __memcpy_simd attribute_hidden;
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extern __typeof (__redirect_memcpy) __memcpy_thunderx attribute_hidden;
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extern __typeof (__redirect_memcpy) __memcpy_thunderx2 attribute_hidden;
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extern __typeof (__redirect_memcpy) __memcpy_falkor attribute_hidden;
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libc_ifunc (__libc_memcpy,
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(IS_THUNDERX (midr)
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? __memcpy_thunderx
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: (IS_FALKOR (midr) || IS_PHECDA (midr)
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? __memcpy_falkor
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: (IS_THUNDERX2 (midr) || IS_THUNDERX2PA (midr)
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? __memcpy_thunderx2
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: (IS_NEOVERSE_N1 (midr) || IS_NEOVERSE_N2 (midr)
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|| IS_NEOVERSE_V1 (midr)
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? __memcpy_simd
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: __memcpy_generic)))));
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# undef memcpy
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strong_alias (__libc_memcpy, memcpy);
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#endif
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