]>
git.ipfire.org Git - thirdparty/gcc.git/blob - libgomp/config/posix/proc.c
1 /* Copyright (C) 2005, 2006, 2008, 2009 Free Software Foundation, Inc.
2 Contributed by Richard Henderson <rth@redhat.com>.
4 This file is part of the GNU OpenMP Library (libgomp).
6 Libgomp is free software; you can redistribute it and/or modify it
7 under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3, or (at your option)
11 Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
13 FOR A PARTICULAR PURPOSE. See the GNU General Public License for
16 Under Section 7 of GPL version 3, you are granted additional
17 permissions described in the GCC Runtime Library Exception, version
18 3.1, as published by the Free Software Foundation.
20 You should have received a copy of the GNU General Public License and
21 a copy of the GCC Runtime Library Exception along with this program;
22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 <http://www.gnu.org/licenses/>. */
25 /* This file contains system specific routines related to counting
26 online processors and dynamic load balancing. It is expected that
27 a system may well want to write special versions of each of these.
29 The following implementation uses a mix of POSIX and BSD routines. */
34 #ifdef HAVE_GETLOADAVG
35 # ifdef HAVE_SYS_LOADAVG_H
36 # include <sys/loadavg.h>
41 /* At startup, determine the default number of threads. It would seem
42 this should be related to the number of cpus online. */
45 gomp_init_num_threads (void)
47 #ifdef _SC_NPROCESSORS_ONLN
48 gomp_global_icv
.nthreads_var
= sysconf (_SC_NPROCESSORS_ONLN
);
52 /* When OMP_DYNAMIC is set, at thread launch determine the number of
53 threads we should spawn for this team. */
54 /* ??? I have no idea what best practice for this is. Surely some
55 function of the number of processors that are *still* online and
56 the load average. Here I use the number of processors online
57 minus the 15 minute load average. */
60 gomp_dynamic_max_threads (void)
62 unsigned n_onln
, loadavg
;
63 unsigned nthreads_var
= gomp_icv (false)->nthreads_var
;
65 #ifdef _SC_NPROCESSORS_ONLN
66 n_onln
= sysconf (_SC_NPROCESSORS_ONLN
);
67 if (n_onln
> nthreads_var
)
68 n_onln
= nthreads_var
;
70 n_onln
= nthreads_var
;
74 #ifdef HAVE_GETLOADAVG
77 if (getloadavg (dloadavg
, 3) == 3)
79 /* Add 0.1 to get a kind of biased rounding. */
80 loadavg
= dloadavg
[2] + 0.1;
85 if (loadavg
>= n_onln
)
88 return n_onln
- loadavg
;
92 omp_get_num_procs (void)
94 #ifdef _SC_NPROCESSORS_ONLN
95 return sysconf (_SC_NPROCESSORS_ONLN
);
97 return gomp_icv (false)->nthreads_var
;
101 ialias (omp_get_num_procs
)