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comparison libgomp/config/linux/proc.c @ 0:a06113de4d67

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author kent <kent@cr.ie.u-ryukyu.ac.jp>
date Fri, 17 Jul 2009 14:47:48 +0900
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children b7f97abdc517
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-1:000000000000 0:a06113de4d67
1 /* Copyright (C) 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
2 Contributed by Jakub Jelinek <jakub@redhat.com>.
3
4 This file is part of the GNU OpenMP Library (libgomp).
5
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)
9 any later version.
10
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
14 more details.
15
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.
19
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/>. */
24
25 /* This file contains system specific routines related to counting
26 online processors and dynamic load balancing. */
27
28 #ifndef _GNU_SOURCE
29 #define _GNU_SOURCE 1
30 #endif
31 #include "libgomp.h"
32 #include <sched.h>
33 #include <stdlib.h>
34 #include <unistd.h>
35 #ifdef HAVE_GETLOADAVG
36 # ifdef HAVE_SYS_LOADAVG_H
37 # include <sys/loadavg.h>
38 # endif
39 #endif
40
41 #ifdef HAVE_PTHREAD_AFFINITY_NP
42 static unsigned long
43 cpuset_popcount (cpu_set_t *cpusetp)
44 {
45 #ifdef CPU_COUNT
46 /* glibc 2.6 and above provide a macro for this. */
47 return CPU_COUNT (cpusetp);
48 #else
49 size_t i;
50 unsigned long ret = 0;
51 extern int check[sizeof (cpusetp->__bits[0]) == sizeof (unsigned long int)];
52
53 (void) check;
54 for (i = 0; i < sizeof (*cpusetp) / sizeof (cpusetp->__bits[0]); i++)
55 {
56 unsigned long int mask = cpusetp->__bits[i];
57 if (mask == 0)
58 continue;
59 ret += __builtin_popcountl (mask);
60 }
61 return ret;
62 #endif
63 }
64 #endif
65
66 /* At startup, determine the default number of threads. It would seem
67 this should be related to the number of cpus online. */
68
69 void
70 gomp_init_num_threads (void)
71 {
72 #ifdef HAVE_PTHREAD_AFFINITY_NP
73 cpu_set_t cpuset;
74
75 if (pthread_getaffinity_np (pthread_self (), sizeof (cpuset), &cpuset) == 0)
76 {
77 /* Count only the CPUs this process can use. */
78 gomp_global_icv.nthreads_var = cpuset_popcount (&cpuset);
79 if (gomp_global_icv.nthreads_var == 0)
80 gomp_global_icv.nthreads_var = 1;
81 return;
82 }
83 #endif
84 #ifdef _SC_NPROCESSORS_ONLN
85 gomp_global_icv.nthreads_var = sysconf (_SC_NPROCESSORS_ONLN);
86 #endif
87 }
88
89 static int
90 get_num_procs (void)
91 {
92 #ifdef HAVE_PTHREAD_AFFINITY_NP
93 cpu_set_t cpuset;
94
95 if (gomp_cpu_affinity == NULL)
96 {
97 /* Count only the CPUs this process can use. */
98 if (pthread_getaffinity_np (pthread_self (), sizeof (cpuset),
99 &cpuset) == 0)
100 {
101 int ret = cpuset_popcount (&cpuset);
102 return ret != 0 ? ret : 1;
103 }
104 }
105 else
106 {
107 size_t idx;
108 static int affinity_cpus;
109
110 /* We can't use pthread_getaffinity_np in this case
111 (we have changed it ourselves, it binds to just one CPU).
112 Count instead the number of different CPUs we are
113 using. */
114 CPU_ZERO (&cpuset);
115 if (affinity_cpus == 0)
116 {
117 int cpus = 0;
118 for (idx = 0; idx < gomp_cpu_affinity_len; idx++)
119 if (! CPU_ISSET (gomp_cpu_affinity[idx], &cpuset))
120 {
121 cpus++;
122 CPU_SET (gomp_cpu_affinity[idx], &cpuset);
123 }
124 affinity_cpus = cpus;
125 }
126 return affinity_cpus;
127 }
128 #endif
129 #ifdef _SC_NPROCESSORS_ONLN
130 return sysconf (_SC_NPROCESSORS_ONLN);
131 #else
132 return gomp_icv (false)->nthreads_var;
133 #endif
134 }
135
136 /* When OMP_DYNAMIC is set, at thread launch determine the number of
137 threads we should spawn for this team. */
138 /* ??? I have no idea what best practice for this is. Surely some
139 function of the number of processors that are *still* online and
140 the load average. Here I use the number of processors online
141 minus the 15 minute load average. */
142
143 unsigned
144 gomp_dynamic_max_threads (void)
145 {
146 unsigned n_onln, loadavg, nthreads_var = gomp_icv (false)->nthreads_var;
147
148 n_onln = get_num_procs ();
149 if (n_onln > nthreads_var)
150 n_onln = nthreads_var;
151
152 loadavg = 0;
153 #ifdef HAVE_GETLOADAVG
154 {
155 double dloadavg[3];
156 if (getloadavg (dloadavg, 3) == 3)
157 {
158 /* Add 0.1 to get a kind of biased rounding. */
159 loadavg = dloadavg[2] + 0.1;
160 }
161 }
162 #endif
163
164 if (loadavg >= n_onln)
165 return 1;
166 else
167 return n_onln - loadavg;
168 }
169
170 int
171 omp_get_num_procs (void)
172 {
173 return get_num_procs ();
174 }
175
176 ialias (omp_get_num_procs)