1 /* Detect the number of processors.
2
3 Copyright (C) 2009-2023 Free Software Foundation, Inc.
4
5 This file is free software: you can redistribute it and/or modify
6 it under the terms of the GNU Lesser General Public License as
7 published by the Free Software Foundation; either version 2.1 of the
8 License, or (at your option) any later version.
9
10 This file 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, see <https://www.gnu.org/licenses/>. */
17
18 /* Written by Glen Lenker and Bruno Haible. */
19
20 /* Allow the use in C++ code. */
21 #ifdef __cplusplus
22 extern "C" {
23 #endif
24
25 /* A "processor" in this context means a thread execution unit, that is either
26 - an execution core in a (possibly multi-core) chip, in a (possibly multi-
27 chip) module, in a single computer, or
28 - a thread execution unit inside a core
29 (hyper-threading, see <https://en.wikipedia.org/wiki/Hyper-threading>).
30 Which of the two definitions is used, is unspecified. */
31
32 enum nproc_query
33 {
34 NPROC_ALL, /* total number of processors */
35 NPROC_CURRENT, /* processors available to the current process */
36 NPROC_CURRENT_OVERRIDABLE /* likewise, but overridable through the
37 OMP_NUM_THREADS environment variable */
38 };
39
40 /* Return the total number of processors. The result is guaranteed to
41 be at least 1. */
42 extern unsigned long int num_processors (enum nproc_query query);
43
44 #ifdef __cplusplus
45 }
46 #endif /* C++ */