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fd6481cf | 1 | /* Copyright (C) 2005, 2006, 2008 Free Software Foundation, Inc. |
1e8e9920 | 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 | |
7 | under the terms of the GNU Lesser General Public License as published by | |
8 | the Free Software Foundation; either version 2.1 of the License, or | |
9 | (at your option) 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 Lesser General Public License for | |
14 | more details. | |
15 | ||
16 | You should have received a copy of the GNU Lesser General Public License | |
17 | along with libgomp; see the file COPYING.LIB. If not, write to the | |
18 | Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, | |
19 | MA 02110-1301, USA. */ | |
20 | ||
21 | /* As a special exception, if you link this library with other files, some | |
22 | of which are compiled with GCC, to produce an executable, this library | |
23 | does not by itself cause the resulting executable to be covered by the | |
24 | GNU General Public License. This exception does not however invalidate | |
25 | any other reasons why the executable file might be covered by the GNU | |
26 | General Public License. */ | |
27 | ||
28 | /* This file contains system specific routines related to counting | |
29 | online processors and dynamic load balancing. It is expected that | |
30 | a system may well want to write special versions of each of these. | |
31 | ||
32 | The following implementation uses a mix of POSIX and BSD routines. */ | |
33 | ||
34 | #include "libgomp.h" | |
35 | #include <unistd.h> | |
36 | #include <stdlib.h> | |
138f59be | 37 | #ifdef HAVE_GETLOADAVG |
38 | # ifdef HAVE_SYS_LOADAVG_H | |
39 | # include <sys/loadavg.h> | |
40 | # endif | |
41 | #endif | |
1e8e9920 | 42 | |
43 | ||
44 | /* At startup, determine the default number of threads. It would seem | |
45 | this should be related to the number of cpus online. */ | |
46 | ||
47 | void | |
48 | gomp_init_num_threads (void) | |
49 | { | |
50 | #ifdef _SC_NPROCESSORS_ONLN | |
fd6481cf | 51 | gomp_global_icv.nthreads_var = sysconf (_SC_NPROCESSORS_ONLN); |
1e8e9920 | 52 | #endif |
53 | } | |
54 | ||
55 | /* When OMP_DYNAMIC is set, at thread launch determine the number of | |
56 | threads we should spawn for this team. */ | |
57 | /* ??? I have no idea what best practice for this is. Surely some | |
58 | function of the number of processors that are *still* online and | |
59 | the load average. Here I use the number of processors online | |
60 | minus the 15 minute load average. */ | |
61 | ||
62 | unsigned | |
63 | gomp_dynamic_max_threads (void) | |
64 | { | |
65 | unsigned n_onln, loadavg; | |
fd6481cf | 66 | unsigned nthreads_var = gomp_icv (false)->nthreads_var; |
1e8e9920 | 67 | |
68 | #ifdef _SC_NPROCESSORS_ONLN | |
69 | n_onln = sysconf (_SC_NPROCESSORS_ONLN); | |
fd6481cf | 70 | if (n_onln > nthreads_var) |
71 | n_onln = nthreads_var; | |
1e8e9920 | 72 | #else |
fd6481cf | 73 | n_onln = nthreads_var; |
1e8e9920 | 74 | #endif |
75 | ||
76 | loadavg = 0; | |
77 | #ifdef HAVE_GETLOADAVG | |
78 | { | |
79 | double dloadavg[3]; | |
80 | if (getloadavg (dloadavg, 3) == 3) | |
81 | { | |
82 | /* Add 0.1 to get a kind of biased rounding. */ | |
83 | loadavg = dloadavg[2] + 0.1; | |
84 | } | |
85 | } | |
86 | #endif | |
87 | ||
88 | if (loadavg >= n_onln) | |
89 | return 1; | |
90 | else | |
91 | return n_onln - loadavg; | |
92 | } | |
93 | ||
94 | int | |
95 | omp_get_num_procs (void) | |
96 | { | |
97 | #ifdef _SC_NPROCESSORS_ONLN | |
98 | return sysconf (_SC_NPROCESSORS_ONLN); | |
99 | #else | |
fd6481cf | 100 | return gomp_icv (false)->nthreads_var; |
1e8e9920 | 101 | #endif |
102 | } | |
103 | ||
104 | ialias (omp_get_num_procs) |