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/* Copyright (C) 2005, 2006 Free Software Foundation, Inc.
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Contributed by Richard Henderson <rth@redhat.com>.
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This file is part of the GNU OpenMP Library (libgomp).
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Libgomp is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
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more details.
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You should have received a copy of the GNU Lesser General Public License
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along with libgomp; see the file COPYING.LIB. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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/* As a special exception, if you link this library with other files, some
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of which are compiled with GCC, to produce an executable, this library
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does not by itself cause the resulting executable to be covered by the
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GNU General Public License. This exception does not however invalidate
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any other reasons why the executable file might be covered by the GNU
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General Public License. */
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/* This file contains system specific routines related to counting
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online processors and dynamic load balancing. It is expected that
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a system may well want to write special versions of each of these.
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The following implementation uses a mix of POSIX and BSD routines. */
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#include "libgomp.h"
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#include <unistd.h>
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#include <stdlib.h>
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#ifdef HAVE_GETLOADAVG
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# ifdef HAVE_SYS_LOADAVG_H
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# include <sys/loadavg.h>
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# endif
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#endif
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/* At startup, determine the default number of threads. It would seem
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this should be related to the number of cpus online. */
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void
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gomp_init_num_threads (void)
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{
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#ifdef _SC_NPROCESSORS_ONLN
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gomp_nthreads_var = sysconf (_SC_NPROCESSORS_ONLN);
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#endif
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}
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/* When OMP_DYNAMIC is set, at thread launch determine the number of
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threads we should spawn for this team. */
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/* ??? I have no idea what best practice for this is. Surely some
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function of the number of processors that are *still* online and
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the load average. Here I use the number of processors online
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minus the 15 minute load average. */
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unsigned
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gomp_dynamic_max_threads (void)
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{
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unsigned n_onln, loadavg;
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#ifdef _SC_NPROCESSORS_ONLN
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n_onln = sysconf (_SC_NPROCESSORS_ONLN);
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if (n_onln > gomp_nthreads_var)
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n_onln = gomp_nthreads_var;
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#else
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n_onln = gomp_nthreads_var;
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#endif
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loadavg = 0;
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#ifdef HAVE_GETLOADAVG
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{
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double dloadavg[3];
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if (getloadavg (dloadavg, 3) == 3)
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{
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/* Add 0.1 to get a kind of biased rounding. */
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loadavg = dloadavg[2] + 0.1;
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}
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}
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#endif
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if (loadavg >= n_onln)
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return 1;
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else
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return n_onln - loadavg;
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}
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int
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omp_get_num_procs (void)
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{
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#ifdef _SC_NPROCESSORS_ONLN
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return sysconf (_SC_NPROCESSORS_ONLN);
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#else
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return gomp_nthreads_var;
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#endif
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}
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ialias (omp_get_num_procs)
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