| 1 | /* Copyright (C) 2005, 2006, 2008, 2009 Free Software Foundation, Inc. |
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| 2 | Contributed by Richard Henderson <rth@redhat.com>. |
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| 3 | |
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| 4 | This file is part of the GNU OpenMP Library (libgomp). |
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| 5 | |
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| 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 |
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| 8 | the Free Software Foundation; either version 3, or (at your option) |
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| 9 | any later version. |
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| 10 | |
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| 11 | Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY |
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| 12 | WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS |
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| 13 | FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
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| 14 | more details. |
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| 15 | |
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| 16 | Under Section 7 of GPL version 3, you are granted additional |
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| 17 | permissions described in the GCC Runtime Library Exception, version |
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| 18 | 3.1, as published by the Free Software Foundation. |
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| 19 | |
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| 20 | You should have received a copy of the GNU General Public License and |
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| 21 | a copy of the GCC Runtime Library Exception along with this program; |
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| 22 | see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
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| 23 | <http://www.gnu.org/licenses/>. */ |
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| 24 | |
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| 25 | /* This file contains system specific routines related to counting |
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| 26 | online processors and dynamic load balancing. It is expected that |
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| 27 | a system may well want to write special versions of each of these. |
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| 28 | |
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| 29 | The following implementation uses a mix of POSIX and BSD routines. */ |
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| 30 | |
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| 31 | #include <gomp/libgomp.h> |
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| 32 | #include <unistd.h> |
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| 33 | #include <stdlib.h> |
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| 34 | #ifdef HAVE_GETLOADAVG |
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| 35 | # ifdef HAVE_SYS_LOADAVG_H |
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| 36 | # include <sys/loadavg.h> |
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| 37 | # endif |
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| 38 | #endif |
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| 39 | |
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| 40 | |
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| 41 | /* At startup, determine the default number of threads. It would seem |
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| 42 | this should be related to the number of cpus online. */ |
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| 43 | |
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| 44 | void |
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| 45 | gomp_init_num_threads (void) |
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| 46 | { |
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| 47 | #ifdef _SC_NPROCESSORS_ONLN |
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| 48 | gomp_global_icv.nthreads_var = sysconf (_SC_NPROCESSORS_ONLN); |
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| 49 | #endif |
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| 50 | } |
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| 51 | |
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| 52 | /* When OMP_DYNAMIC is set, at thread launch determine the number of |
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| 53 | threads we should spawn for this team. */ |
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| 54 | /* ??? I have no idea what best practice for this is. Surely some |
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| 55 | function of the number of processors that are *still* online and |
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| 56 | the load average. Here I use the number of processors online |
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| 57 | minus the 15 minute load average. */ |
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| 58 | |
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| 59 | unsigned |
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| 60 | gomp_dynamic_max_threads (void) |
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| 61 | { |
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| 62 | unsigned n_onln, loadavg; |
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| 63 | unsigned nthreads_var = gomp_icv (false)->nthreads_var; |
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| 64 | |
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| 65 | #ifdef _SC_NPROCESSORS_ONLN |
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| 66 | n_onln = sysconf (_SC_NPROCESSORS_ONLN); |
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| 67 | if (n_onln > nthreads_var) |
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| 68 | n_onln = nthreads_var; |
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| 69 | #else |
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| 70 | n_onln = nthreads_var; |
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| 71 | #endif |
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| 72 | |
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| 73 | loadavg = 0; |
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| 74 | #ifdef HAVE_GETLOADAVG |
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| 75 | { |
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| 76 | double dloadavg[3]; |
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| 77 | if (getloadavg (dloadavg, 3) == 3) |
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| 78 | { |
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| 79 | /* Add 0.1 to get a kind of biased rounding. */ |
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| 80 | loadavg = dloadavg[2] + 0.1; |
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| 81 | } |
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| 82 | } |
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| 83 | #endif |
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| 84 | |
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| 85 | if (loadavg >= n_onln) |
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| 86 | return 1; |
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| 87 | else |
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| 88 | return n_onln - loadavg; |
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| 89 | } |
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| 90 | |
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| 91 | int |
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| 92 | omp_get_num_procs(void) |
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| 93 | { |
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| 94 | #ifdef _SC_NPROCESSORS_ONLN |
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| 95 | return sysconf (_SC_NPROCESSORS_ONLN); |
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| 96 | #else |
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| 97 | return gomp_icv (false)->nthreads_var; |
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| 98 | #endif |
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| 99 | } |
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| 100 | |
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| 101 | ialias (omp_get_num_procs) |
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