1 /* Copyright (C) 2005-2015 Free Software Foundation, Inc.
2 Contributed by Richard Henderson <rth@redhat.com>.
4 This file is part of the GNU Offloading and Multi Processing Library
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)
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
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.
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/>. */
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.
30 The following implementation uses a mix of POSIX and BSD routines. */
35 #ifdef HAVE_GETLOADAVG
36 # ifdef HAVE_SYS_LOADAVG_H
37 # include <sys/loadavg.h>
42 /* At startup, determine the default number of threads. It would seem
43 this should be related to the number of cpus online. */
46 gomp_init_num_threads (void)
48 #ifdef _SC_NPROCESSORS_ONLN
49 gomp_global_icv
.nthreads_var
= sysconf (_SC_NPROCESSORS_ONLN
);
53 /* When OMP_DYNAMIC is set, at thread launch determine the number of
54 threads we should spawn for this team. */
55 /* ??? I have no idea what best practice for this is. Surely some
56 function of the number of processors that are *still* online and
57 the load average. Here I use the number of processors online
58 minus the 15 minute load average. */
61 gomp_dynamic_max_threads (void)
63 unsigned n_onln
, loadavg
;
64 unsigned nthreads_var
= gomp_icv (false)->nthreads_var
;
66 #ifdef _SC_NPROCESSORS_ONLN
67 n_onln
= sysconf (_SC_NPROCESSORS_ONLN
);
68 if (n_onln
> nthreads_var
)
69 n_onln
= nthreads_var
;
71 n_onln
= nthreads_var
;
75 #ifdef HAVE_GETLOADAVG
78 if (getloadavg (dloadavg
, 3) == 3)
80 /* Add 0.1 to get a kind of biased rounding. */
81 loadavg
= dloadavg
[2] + 0.1;
86 if (loadavg
>= n_onln
)
89 return n_onln
- loadavg
;
93 omp_get_num_procs (void)
95 #ifdef _SC_NPROCESSORS_ONLN
96 return sysconf (_SC_NPROCESSORS_ONLN
);
98 return gomp_icv (false)->nthreads_var
;
102 ialias (omp_get_num_procs
)