1 /* Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010
2 Free Software Foundation, Inc.
3 Contributed by Jakub Jelinek <jakub@redhat.com>.
5 This file is part of the GNU OpenMP Library (libgomp).
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. */
36 #ifdef HAVE_GETLOADAVG
37 # ifdef HAVE_SYS_LOADAVG_H
38 # include <sys/loadavg.h>
42 #ifdef HAVE_PTHREAD_AFFINITY_NP
44 gomp_cpuset_popcount (cpu_set_t *cpusetp)
47 /* glibc 2.6 and above provide a macro for this. */
48 return CPU_COUNT (cpusetp);
51 unsigned long ret = 0;
52 extern int check[sizeof (cpusetp->__bits[0]) == sizeof (unsigned long int)];
55 for (i = 0; i < sizeof (*cpusetp) / sizeof (cpusetp->__bits[0]); i++)
57 unsigned long int mask = cpusetp->__bits[i];
60 ret += __builtin_popcountl (mask);
67 /* At startup, determine the default number of threads. It would seem
68 this should be related to the number of cpus online. */
71 gomp_init_num_threads (void)
73 #ifdef HAVE_PTHREAD_AFFINITY_NP
76 if (pthread_getaffinity_np (pthread_self (), sizeof (cpuset), &cpuset) == 0)
78 /* Count only the CPUs this process can use. */
79 gomp_global_icv.nthreads_var = gomp_cpuset_popcount (&cpuset);
80 if (gomp_global_icv.nthreads_var == 0)
81 gomp_global_icv.nthreads_var = 1;
85 #ifdef _SC_NPROCESSORS_ONLN
86 gomp_global_icv.nthreads_var = sysconf (_SC_NPROCESSORS_ONLN);
93 #ifdef HAVE_PTHREAD_AFFINITY_NP
96 if (gomp_cpu_affinity == NULL)
98 /* Count only the CPUs this process can use. */
99 if (pthread_getaffinity_np (pthread_self (), sizeof (cpuset),
102 int ret = gomp_cpuset_popcount (&cpuset);
103 return ret != 0 ? ret : 1;
108 /* We can't use pthread_getaffinity_np in this case
109 (we have changed it ourselves, it binds to just one CPU).
110 Count instead the number of different CPUs we are
111 using. gomp_init_affinity updated gomp_available_cpus to
112 the number of CPUs in the GOMP_AFFINITY mask that we are
113 allowed to use though. */
114 return gomp_available_cpus;
117 #ifdef _SC_NPROCESSORS_ONLN
118 return sysconf (_SC_NPROCESSORS_ONLN);
120 return gomp_icv (false)->nthreads_var;
124 /* When OMP_DYNAMIC is set, at thread launch determine the number of
125 threads we should spawn for this team. */
126 /* ??? I have no idea what best practice for this is. Surely some
127 function of the number of processors that are *still* online and
128 the load average. Here I use the number of processors online
129 minus the 15 minute load average. */
132 gomp_dynamic_max_threads (void)
134 unsigned n_onln, loadavg, nthreads_var = gomp_icv (false)->nthreads_var;
136 n_onln = get_num_procs ();
137 if (n_onln > nthreads_var)
138 n_onln = nthreads_var;
141 #ifdef HAVE_GETLOADAVG
144 if (getloadavg (dloadavg, 3) == 3)
146 /* Add 0.1 to get a kind of biased rounding. */
147 loadavg = dloadavg[2] + 0.1;
152 if (loadavg >= n_onln)
155 return n_onln - loadavg;
159 omp_get_num_procs (void)
161 return get_num_procs ();
164 ialias (omp_get_num_procs)