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/* x86 cache info.
Copyright (C) 2020-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <assert.h>
#include <unistd.h>
#include <cpuid.h>
#include <cpu-features.h>
#define TUNABLE_NAMESPACE cpu
#include <unistd.h> /* Get STDOUT_FILENO for _dl_printf. */
#include <elf/dl-tunables.h>
#if IS_IN (libc)
/* Data cache size for use in memory and string routines, typically
L1 size, rounded to multiple of 256 bytes. */
long int __x86_data_cache_size_half attribute_hidden = 32 * 1024 / 2;
long int __x86_data_cache_size attribute_hidden = 32 * 1024;
/* Shared cache size for use in memory and string routines, typically
L2 or L3 size, rounded to multiple of 256 bytes. */
long int __x86_shared_cache_size_half attribute_hidden = 1024 * 1024 / 2;
long int __x86_shared_cache_size attribute_hidden = 1024 * 1024;
/* Threshold to use non temporal store. */
long int __x86_shared_non_temporal_threshold attribute_hidden;
/* Threshold to use Enhanced REP MOVSB. */
long int __x86_rep_movsb_threshold attribute_hidden = 2048;
/* Threshold to use Enhanced REP STOSB. */
long int __x86_rep_stosb_threshold attribute_hidden = 2048;
/* Threshold to stop using Enhanced REP MOVSB. */
long int __x86_rep_movsb_stop_threshold attribute_hidden;
/* A bit-wise OR of string/memory requirements for optimal performance
e.g. X86_STRING_CONTROL_AVOID_SHORT_DISTANCE_REP_MOVSB. These bits
are used at runtime to tune implementation behavior. */
int __x86_string_control attribute_hidden;
static void
init_cacheinfo (void)
{
const struct cpu_features *cpu_features = __get_cpu_features ();
long int data = cpu_features->data_cache_size;
/* Round data cache size to multiple of 256 bytes. */
data = data & ~255L;
if (data > 0)
{
__x86_data_cache_size_half = data / 2;
__x86_data_cache_size = data;
}
long int shared = cpu_features->shared_cache_size;
/* Round shared cache size to multiple of 256 bytes. */
shared = shared & ~255L;
if (shared > 0)
{
__x86_shared_cache_size_half = shared / 2;
__x86_shared_cache_size = shared;
}
__x86_shared_non_temporal_threshold
= cpu_features->non_temporal_threshold;
__x86_rep_movsb_threshold = cpu_features->rep_movsb_threshold;
__x86_rep_stosb_threshold = cpu_features->rep_stosb_threshold;
__x86_rep_movsb_stop_threshold = cpu_features->rep_movsb_stop_threshold;
if (CPU_FEATURES_ARCH_P (cpu_features, Avoid_Short_Distance_REP_MOVSB))
__x86_string_control
|= X86_STRING_CONTROL_AVOID_SHORT_DISTANCE_REP_MOVSB;
}
#endif
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