1*404b540aSrobert /* Copyright (C) 2005, 2006 Free Software Foundation, Inc.
2*404b540aSrobert Contributed by Richard Henderson <rth@redhat.com>.
3*404b540aSrobert
4*404b540aSrobert This file is part of the GNU OpenMP Library (libgomp).
5*404b540aSrobert
6*404b540aSrobert Libgomp is free software; you can redistribute it and/or modify it
7*404b540aSrobert under the terms of the GNU Lesser General Public License as published by
8*404b540aSrobert the Free Software Foundation; either version 2.1 of the License, or
9*404b540aSrobert (at your option) any later version.
10*404b540aSrobert
11*404b540aSrobert Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
12*404b540aSrobert WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
13*404b540aSrobert FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
14*404b540aSrobert more details.
15*404b540aSrobert
16*404b540aSrobert You should have received a copy of the GNU Lesser General Public License
17*404b540aSrobert along with libgomp; see the file COPYING.LIB. If not, write to the
18*404b540aSrobert Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
19*404b540aSrobert MA 02110-1301, USA. */
20*404b540aSrobert
21*404b540aSrobert /* As a special exception, if you link this library with other files, some
22*404b540aSrobert of which are compiled with GCC, to produce an executable, this library
23*404b540aSrobert does not by itself cause the resulting executable to be covered by the
24*404b540aSrobert GNU General Public License. This exception does not however invalidate
25*404b540aSrobert any other reasons why the executable file might be covered by the GNU
26*404b540aSrobert General Public License. */
27*404b540aSrobert
28*404b540aSrobert /* This file contains system specific routines related to counting
29*404b540aSrobert online processors and dynamic load balancing. It is expected that
30*404b540aSrobert a system may well want to write special versions of each of these.
31*404b540aSrobert
32*404b540aSrobert The following implementation uses a mix of POSIX and BSD routines. */
33*404b540aSrobert
34*404b540aSrobert #include "libgomp.h"
35*404b540aSrobert #include <unistd.h>
36*404b540aSrobert #include <stdlib.h>
37*404b540aSrobert #ifdef HAVE_GETLOADAVG
38*404b540aSrobert # ifdef HAVE_SYS_LOADAVG_H
39*404b540aSrobert # include <sys/loadavg.h>
40*404b540aSrobert # endif
41*404b540aSrobert #endif
42*404b540aSrobert
43*404b540aSrobert
44*404b540aSrobert /* At startup, determine the default number of threads. It would seem
45*404b540aSrobert this should be related to the number of cpus online. */
46*404b540aSrobert
47*404b540aSrobert void
gomp_init_num_threads(void)48*404b540aSrobert gomp_init_num_threads (void)
49*404b540aSrobert {
50*404b540aSrobert #ifdef _SC_NPROCESSORS_ONLN
51*404b540aSrobert gomp_nthreads_var = sysconf (_SC_NPROCESSORS_ONLN);
52*404b540aSrobert #endif
53*404b540aSrobert }
54*404b540aSrobert
55*404b540aSrobert /* When OMP_DYNAMIC is set, at thread launch determine the number of
56*404b540aSrobert threads we should spawn for this team. */
57*404b540aSrobert /* ??? I have no idea what best practice for this is. Surely some
58*404b540aSrobert function of the number of processors that are *still* online and
59*404b540aSrobert the load average. Here I use the number of processors online
60*404b540aSrobert minus the 15 minute load average. */
61*404b540aSrobert
62*404b540aSrobert unsigned
gomp_dynamic_max_threads(void)63*404b540aSrobert gomp_dynamic_max_threads (void)
64*404b540aSrobert {
65*404b540aSrobert unsigned n_onln, loadavg;
66*404b540aSrobert
67*404b540aSrobert #ifdef _SC_NPROCESSORS_ONLN
68*404b540aSrobert n_onln = sysconf (_SC_NPROCESSORS_ONLN);
69*404b540aSrobert if (n_onln > gomp_nthreads_var)
70*404b540aSrobert n_onln = gomp_nthreads_var;
71*404b540aSrobert #else
72*404b540aSrobert n_onln = gomp_nthreads_var;
73*404b540aSrobert #endif
74*404b540aSrobert
75*404b540aSrobert loadavg = 0;
76*404b540aSrobert #ifdef HAVE_GETLOADAVG
77*404b540aSrobert {
78*404b540aSrobert double dloadavg[3];
79*404b540aSrobert if (getloadavg (dloadavg, 3) == 3)
80*404b540aSrobert {
81*404b540aSrobert /* Add 0.1 to get a kind of biased rounding. */
82*404b540aSrobert loadavg = dloadavg[2] + 0.1;
83*404b540aSrobert }
84*404b540aSrobert }
85*404b540aSrobert #endif
86*404b540aSrobert
87*404b540aSrobert if (loadavg >= n_onln)
88*404b540aSrobert return 1;
89*404b540aSrobert else
90*404b540aSrobert return n_onln - loadavg;
91*404b540aSrobert }
92*404b540aSrobert
93*404b540aSrobert int
omp_get_num_procs(void)94*404b540aSrobert omp_get_num_procs (void)
95*404b540aSrobert {
96*404b540aSrobert #ifdef _SC_NPROCESSORS_ONLN
97*404b540aSrobert return sysconf (_SC_NPROCESSORS_ONLN);
98*404b540aSrobert #else
99*404b540aSrobert return gomp_nthreads_var;
100*404b540aSrobert #endif
101*404b540aSrobert }
102*404b540aSrobert
103*404b540aSrobert ialias (omp_get_num_procs)
104