1 /* Detect the number of processors.
3 Copyright (C) 2009-2011 Free Software Foundation, Inc.
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2, or (at your option)
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 General Public License for more details.
15 You should have received a copy of the GNU 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. */
19 /* Written by Glen Lenker and Bruno Haible. */
21 /* Allow the use in C++ code. */
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. */
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 */
41 /* Return the total number of processors. The result is guaranteed to
43 extern unsigned long int num_processors (enum nproc_query query);