sysdeps/x86/cacheinfo.h

   1 /* x86 cache info.
   2    Copyright (C) 2020-2021 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <assert.h>
  20 #include <unistd.h>
  21 #include <cpuid.h>
  22 #include <cpu-features.h>
  23
  24 #if HAVE_TUNABLES
  25 # define TUNABLE_NAMESPACE cpu
  26 # include <unistd.h>            /* Get STDOUT_FILENO for _dl_printf.  */
  27 # include <elf/dl-tunables.h>
  28 #endif
  29
  30 #if IS_IN (libc)
  31 /* Data cache size for use in memory and string routines, typically
  32    L1 size, rounded to multiple of 256 bytes.  */
  33 long int __x86_data_cache_size_half attribute_hidden = 32 * 1024 / 2;
  34 long int __x86_data_cache_size attribute_hidden = 32 * 1024;
  35 /* Similar to __x86_data_cache_size_half, but not rounded.  */
  36 long int __x86_raw_data_cache_size_half attribute_hidden = 32 * 1024 / 2;
  37 /* Similar to __x86_data_cache_size, but not rounded.  */
  38 long int __x86_raw_data_cache_size attribute_hidden = 32 * 1024;
  39 /* Shared cache size for use in memory and string routines, typically
  40    L2 or L3 size, rounded to multiple of 256 bytes.  */
  41 long int __x86_shared_cache_size_half attribute_hidden = 1024 * 1024 / 2;
  42 long int __x86_shared_cache_size attribute_hidden = 1024 * 1024;
  43 /* Similar to __x86_shared_cache_size_half, but not rounded.  */
  44 long int __x86_raw_shared_cache_size_half attribute_hidden = 1024 * 1024 / 2;
  45 /* Similar to __x86_shared_cache_size, but not rounded.  */
  46 long int __x86_raw_shared_cache_size attribute_hidden = 1024 * 1024;
  47
  48 /* Threshold to use non temporal store.  */
  49 long int __x86_shared_non_temporal_threshold attribute_hidden;
  50
  51 /* Threshold to use Enhanced REP MOVSB.  */
  52 long int __x86_rep_movsb_threshold attribute_hidden = 2048;
  53
  54 /* Threshold to use Enhanced REP STOSB.  */
  55 long int __x86_rep_stosb_threshold attribute_hidden = 2048;
  56
  57 /* Threshold to stop using Enhanced REP MOVSB.  */
  58 long int __x86_rep_movsb_stop_threshold attribute_hidden;
  59
  60 static void
  61 init_cacheinfo (void)
  62 {
  63   const struct cpu_features *cpu_features = __get_cpu_features ();
  64   long int data = cpu_features->data_cache_size;
  65   __x86_raw_data_cache_size_half = data / 2;
  66   __x86_raw_data_cache_size = data;
  67   /* Round data cache size to multiple of 256 bytes.  */
  68   data = data & ~255L;
  69   __x86_data_cache_size_half = data / 2;
  70   __x86_data_cache_size = data;
  71
  72   long int shared = cpu_features->shared_cache_size;
  73   __x86_raw_shared_cache_size_half = shared / 2;
  74   __x86_raw_shared_cache_size = shared;
  75   /* Round shared cache size to multiple of 256 bytes.  */
  76   shared = shared & ~255L;
  77   __x86_shared_cache_size_half = shared / 2;
  78   __x86_shared_cache_size = shared;
  79
  80   __x86_shared_non_temporal_threshold
  81     = cpu_features->non_temporal_threshold;
  82
  83   __x86_rep_movsb_threshold = cpu_features->rep_movsb_threshold;
  84   __x86_rep_stosb_threshold = cpu_features->rep_stosb_threshold;
  85   __x86_rep_movsb_stop_threshold =  cpu_features->rep_movsb_stop_threshold;
  86 }
  87 #endif