libgomp/config/mingw32/proc.c

   1 /* Copyright (C) 2007-2024 Free Software Foundation, Inc.
   2    Contributed by Danny Smith <dannysmith@users.sourceforge.net>
   3
   4    This file is part of the GNU Offloading and Multi Processing Library
   5    (libgomp).
   6
   7    Libgomp is free software; you can redistribute it and/or modify it
   8    under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3, or (at your option)
  10    any later version.
  11
  12    Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
  13    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  14    FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  15    more details.
  16
  17    Under Section 7 of GPL version 3, you are granted additional
  18    permissions described in the GCC Runtime Library Exception, version
  19    3.1, as published by the Free Software Foundation.
  20
  21    You should have received a copy of the GNU General Public License and
  22    a copy of the GCC Runtime Library Exception along with this program;
  23    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24    <http://www.gnu.org/licenses/>.  */
  25
  26 /* This file contains system specific routines related to counting
  27    online processors and dynamic load balancing.  It is expected that
  28    a system may well want to write special versions of each of these.
  29
  30    The following implementation uses win32 API routines.  */
  31
  32 #include "libgomp.h"
  33 #define WIN32_LEAN_AND_MEAN
  34 #include <windows.h>
  35
  36 /* Count the CPU's currently available to this process.  */
  37 static unsigned int
  38 count_avail_process_cpus ()
  39 {
  40   DWORD_PTR process_cpus;
  41   DWORD_PTR system_cpus;
  42
  43   if (GetProcessAffinityMask (GetCurrentProcess (),
  44                               &process_cpus, &system_cpus))
  45     {
  46       unsigned int count;
  47       for (count = 0; process_cpus != 0; process_cpus >>= 1)
  48         if (process_cpus & 1)
  49           count++;
  50       return count;
  51     }
  52   return 1;
  53 }
  54
  55 /* At startup, determine the default number of threads.  It would seem
  56    this should be related to the number of cpus available to the process.  */
  57
  58 void
  59 gomp_init_num_threads (void)
  60 {
  61   gomp_global_icv.nthreads_var = count_avail_process_cpus ();
  62 }
  63
  64 /* When OMP_DYNAMIC is set, at thread launch determine the number of
  65    threads we should spawn for this team.  FIXME:  How do we adjust for
  66    load average on MS Windows?  */
  67
  68 unsigned
  69 gomp_dynamic_max_threads (void)
  70 {
  71   unsigned int n_onln = count_avail_process_cpus ();
  72   unsigned int nthreads_var = gomp_icv (false)->nthreads_var;
  73   return n_onln > nthreads_var ? nthreads_var : n_onln;
  74 }
  75
  76 int
  77 omp_get_num_procs (void)
  78 {
  79   return count_avail_process_cpus ();
  80 }
  81
  82 ialias (omp_get_num_procs)