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748086b7 | 1 | /* Copyright (C) 2005, 2006, 2008, 2009 Free Software Foundation, Inc. |
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2 | Contributed by Richard Henderson <rth@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 | |
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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. | |
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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 | |
748086b7 | 13 | FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
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14 | more details. |
15 | ||
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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/>. */ | |
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24 | |
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. | |
28 | ||
29 | The following implementation uses a mix of POSIX and BSD routines. */ | |
30 | ||
31 | #include "libgomp.h" | |
32 | #include <unistd.h> | |
33 | #include <stdlib.h> | |
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34 | #ifdef HAVE_GETLOADAVG |
35 | # ifdef HAVE_SYS_LOADAVG_H | |
36 | # include <sys/loadavg.h> | |
37 | # endif | |
38 | #endif | |
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39 | |
40 | ||
41 | /* At startup, determine the default number of threads. It would seem | |
42 | this should be related to the number of cpus online. */ | |
43 | ||
44 | void | |
45 | gomp_init_num_threads (void) | |
46 | { | |
47 | #ifdef _SC_NPROCESSORS_ONLN | |
a68ab351 | 48 | gomp_global_icv.nthreads_var = sysconf (_SC_NPROCESSORS_ONLN); |
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49 | #endif |
50 | } | |
51 | ||
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. */ | |
58 | ||
59 | unsigned | |
60 | gomp_dynamic_max_threads (void) | |
61 | { | |
62 | unsigned n_onln, loadavg; | |
a68ab351 | 63 | unsigned nthreads_var = gomp_icv (false)->nthreads_var; |
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64 | |
65 | #ifdef _SC_NPROCESSORS_ONLN | |
66 | n_onln = sysconf (_SC_NPROCESSORS_ONLN); | |
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67 | if (n_onln > nthreads_var) |
68 | n_onln = nthreads_var; | |
953ff289 | 69 | #else |
a68ab351 | 70 | n_onln = nthreads_var; |
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71 | #endif |
72 | ||
73 | loadavg = 0; | |
74 | #ifdef HAVE_GETLOADAVG | |
75 | { | |
76 | double dloadavg[3]; | |
77 | if (getloadavg (dloadavg, 3) == 3) | |
78 | { | |
79 | /* Add 0.1 to get a kind of biased rounding. */ | |
80 | loadavg = dloadavg[2] + 0.1; | |
81 | } | |
82 | } | |
83 | #endif | |
84 | ||
85 | if (loadavg >= n_onln) | |
86 | return 1; | |
87 | else | |
88 | return n_onln - loadavg; | |
89 | } | |
90 | ||
91 | int | |
92 | omp_get_num_procs (void) | |
93 | { | |
94 | #ifdef _SC_NPROCESSORS_ONLN | |
95 | return sysconf (_SC_NPROCESSORS_ONLN); | |
96 | #else | |
a68ab351 | 97 | return gomp_icv (false)->nthreads_var; |
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98 | #endif |
99 | } | |
100 | ||
101 | ialias (omp_get_num_procs) |