115 lines
3.1 KiB
C
115 lines
3.1 KiB
C
/* Copyright (C) 2005, 2006, 2008, 2009 Free Software Foundation, Inc.
|
|
Contributed by Richard Henderson <rth@redhat.com>.
|
|
|
|
This file is part of the GNU OpenMP Library (libgomp).
|
|
|
|
Libgomp is free software; you can redistribute it and/or modify it
|
|
under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 3, or (at your option)
|
|
any later version.
|
|
|
|
Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
|
|
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
|
|
FOR A PARTICULAR PURPOSE. See the GNU General Public License for
|
|
more details.
|
|
|
|
Under Section 7 of GPL version 3, you are granted additional
|
|
permissions described in the GCC Runtime Library Exception, version
|
|
3.1, as published by the Free Software Foundation.
|
|
|
|
You should have received a copy of the GNU General Public License and
|
|
a copy of the GCC Runtime Library Exception along with this program;
|
|
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
/* This file contains system specific routines related to counting
|
|
online processors and dynamic load balancing. It is expected that
|
|
a system may well want to write special versions of each of these.
|
|
|
|
The following implementation uses a mix of POSIX and BSD routines. */
|
|
|
|
#include "libgomp.h"
|
|
#include <unistd.h>
|
|
#include <stdlib.h>
|
|
#ifdef HAVE_GETLOADAVG
|
|
# ifdef HAVE_SYS_LOADAVG_H
|
|
# include <sys/loadavg.h>
|
|
# endif
|
|
#endif
|
|
#ifdef HAVE_SYS_SYSCTL_H
|
|
# include <sys/sysctl.h>
|
|
#endif
|
|
|
|
static int
|
|
get_num_procs (void)
|
|
{
|
|
#ifdef _SC_NPROCESSORS_ONLN
|
|
return sysconf (_SC_NPROCESSORS_ONLN);
|
|
#elif defined HW_NCPU
|
|
int ncpus = 1;
|
|
size_t len = sizeof(ncpus);
|
|
sysctl((int[2]) {CTL_HW, HW_NCPU}, 2, &ncpus, &len, NULL, 0);
|
|
return ncpus;
|
|
#else
|
|
return 0;
|
|
#endif
|
|
}
|
|
|
|
/* At startup, determine the default number of threads. It would seem
|
|
this should be related to the number of cpus online. */
|
|
|
|
void
|
|
gomp_init_num_threads (void)
|
|
{
|
|
int ncpus = get_num_procs ();
|
|
|
|
if (ncpus > 0)
|
|
gomp_global_icv.nthreads_var = ncpus;
|
|
}
|
|
|
|
/* When OMP_DYNAMIC is set, at thread launch determine the number of
|
|
threads we should spawn for this team. */
|
|
/* ??? I have no idea what best practice for this is. Surely some
|
|
function of the number of processors that are *still* online and
|
|
the load average. Here I use the number of processors online
|
|
minus the 15 minute load average. */
|
|
|
|
unsigned
|
|
gomp_dynamic_max_threads (void)
|
|
{
|
|
unsigned n_onln, loadavg;
|
|
unsigned nthreads_var = gomp_icv (false)->nthreads_var;
|
|
|
|
n_onln = get_num_procs ();
|
|
if (!n_onln || n_onln > nthreads_var)
|
|
n_onln = nthreads_var;
|
|
|
|
loadavg = 0;
|
|
#ifdef HAVE_GETLOADAVG
|
|
{
|
|
double dloadavg[3];
|
|
if (getloadavg (dloadavg, 3) == 3)
|
|
{
|
|
/* Add 0.1 to get a kind of biased rounding. */
|
|
loadavg = dloadavg[2] + 0.1;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
if (loadavg >= n_onln)
|
|
return 1;
|
|
else
|
|
return n_onln - loadavg;
|
|
}
|
|
|
|
int
|
|
omp_get_num_procs (void)
|
|
{
|
|
int ncpus = get_num_procs ();
|
|
if (ncpus <= 0)
|
|
ncpus = gomp_icv (false)->nthreads_var;
|
|
return ncpus;
|
|
}
|
|
|
|
ialias (omp_get_num_procs)
|