lib/nproc.h

   1 /* Detect the number of processors.
   2
   3    Copyright (C) 2009-2011 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU Lesser General Public License as published by
   7    the Free Software Foundation; either version 2, or (at your option)
   8    any later version.
   9
  10    This program 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
  13    GNU Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public License
  16    along with this program; if not, write to the Free Software Foundation,
  17    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  18
  19 /* Written by Glen Lenker and Bruno Haible.  */
  20
  21 /* Allow the use in C++ code.  */
  22 #ifdef __cplusplus
  23 extern "C" {
  24 #endif
  25
  26 /* A "processor" in this context means a thread execution unit, that is either
  27    - an execution core in a (possibly multi-core) chip, in a (possibly multi-
  28      chip) module, in a single computer, or
  29    - a thread execution unit inside a core
  30      (hyper-threading, see <http://en.wikipedia.org/wiki/Hyper-threading>).
  31    Which of the two definitions is used, is unspecified.  */
  32
  33 enum nproc_query
  34 {
  35   NPROC_ALL,                 /* total number of processors */
  36   NPROC_CURRENT,             /* processors available to the current process */
  37   NPROC_CURRENT_OVERRIDABLE  /* likewise, but overridable through the
  38                                 OMP_NUM_THREADS environment variable */
  39 };
  40
  41 /* Return the total number of processors.  The result is guaranteed to
  42    be at least 1.  */
  43 extern unsigned long int num_processors (enum nproc_query query);
  44
  45 #ifdef __cplusplus
  46 }
  47 #endif /* C++ */