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- /* Copyright (C) 2005-2022 Free Software Foundation, Inc.
- Contributed by Jakub Jelinek <jakub@redhat.com>.
- This file is part of the GNU Offloading and Multi Processing 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. */
- #ifndef _GNU_SOURCE
- #define _GNU_SOURCE 1
- #endif
- #include "libgomp.h"
- #include "proc.h"
- #include <errno.h>
- #include <stdlib.h>
- #include <unistd.h>
- #ifdef HAVE_GETLOADAVG
- # ifdef HAVE_SYS_LOADAVG_H
- # include <sys/loadavg.h>
- # endif
- #endif
- #ifdef HAVE_PTHREAD_AFFINITY_NP
- unsigned long gomp_cpuset_size;
- static unsigned long gomp_get_cpuset_size;
- cpu_set_t *gomp_cpusetp;
- unsigned long
- gomp_cpuset_popcount (unsigned long cpusetsize, cpu_set_t *cpusetp)
- {
- #ifdef CPU_COUNT_S
- /* glibc 2.7 and above provide a macro for this. */
- return CPU_COUNT_S (cpusetsize, cpusetp);
- #else
- #ifdef CPU_COUNT
- if (cpusetsize == sizeof (cpu_set_t))
- /* glibc 2.6 and above provide a macro for this. */
- return CPU_COUNT (cpusetp);
- #endif
- size_t i;
- unsigned long ret = 0;
- extern int check[sizeof (cpusetp->__bits[0]) == sizeof (unsigned long int)
- ? 1 : -1] __attribute__((unused));
- for (i = 0; i < cpusetsize / sizeof (cpusetp->__bits[0]); i++)
- {
- unsigned long int mask = cpusetp->__bits[i];
- if (mask == 0)
- continue;
- ret += __builtin_popcountl (mask);
- }
- return ret;
- #endif
- }
- #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)
- {
- #ifdef HAVE_PTHREAD_AFFINITY_NP
- #if defined (_SC_NPROCESSORS_CONF) && defined (CPU_ALLOC_SIZE)
- gomp_cpuset_size = sysconf (_SC_NPROCESSORS_CONF);
- gomp_cpuset_size = CPU_ALLOC_SIZE (gomp_cpuset_size);
- #else
- gomp_cpuset_size = sizeof (cpu_set_t);
- #endif
- gomp_cpusetp = (cpu_set_t *) gomp_malloc (gomp_cpuset_size);
- do
- {
- int ret = pthread_getaffinity_np (pthread_self (), gomp_cpuset_size,
- gomp_cpusetp);
- if (ret == 0)
- {
- /* Count only the CPUs this process can use. */
- gomp_global_icv.nthreads_var
- = gomp_cpuset_popcount (gomp_cpuset_size, gomp_cpusetp);
- if (gomp_global_icv.nthreads_var == 0)
- break;
- gomp_get_cpuset_size = gomp_cpuset_size;
- #ifdef CPU_ALLOC_SIZE
- unsigned long i;
- for (i = gomp_cpuset_size * 8; i; i--)
- if (CPU_ISSET_S (i - 1, gomp_cpuset_size, gomp_cpusetp))
- break;
- gomp_cpuset_size = CPU_ALLOC_SIZE (i);
- #endif
- return;
- }
- if (ret != EINVAL)
- break;
- #ifdef CPU_ALLOC_SIZE
- if (gomp_cpuset_size < sizeof (cpu_set_t))
- gomp_cpuset_size = sizeof (cpu_set_t);
- else
- gomp_cpuset_size = gomp_cpuset_size * 2;
- if (gomp_cpuset_size < 8 * sizeof (cpu_set_t))
- gomp_cpusetp
- = (cpu_set_t *) gomp_realloc (gomp_cpusetp, gomp_cpuset_size);
- else
- {
- /* Avoid gomp_fatal if too large memory allocation would be
- requested, e.g. kernel returning EINVAL all the time. */
- void *p = realloc (gomp_cpusetp, gomp_cpuset_size);
- if (p == NULL)
- break;
- gomp_cpusetp = (cpu_set_t *) p;
- }
- #else
- break;
- #endif
- }
- while (1);
- gomp_cpuset_size = 0;
- gomp_global_icv.nthreads_var = 1;
- free (gomp_cpusetp);
- gomp_cpusetp = NULL;
- #endif
- #ifdef _SC_NPROCESSORS_ONLN
- gomp_global_icv.nthreads_var = sysconf (_SC_NPROCESSORS_ONLN);
- #endif
- }
- static int
- get_num_procs (void)
- {
- #ifdef HAVE_PTHREAD_AFFINITY_NP
- if (gomp_places_list == NULL)
- {
- /* Count only the CPUs this process can use. */
- if (gomp_cpusetp
- && pthread_getaffinity_np (pthread_self (), gomp_get_cpuset_size,
- gomp_cpusetp) == 0)
- {
- int ret = gomp_cpuset_popcount (gomp_get_cpuset_size, gomp_cpusetp);
- return ret != 0 ? ret : 1;
- }
- }
- else
- {
- /* We can't use pthread_getaffinity_np in this case
- (we have changed it ourselves, it binds to just one CPU).
- Count instead the number of different CPUs we are
- using. gomp_init_affinity updated gomp_available_cpus to
- the number of CPUs in the GOMP_AFFINITY mask that we are
- allowed to use though. */
- return gomp_available_cpus;
- }
- #endif
- #ifdef _SC_NPROCESSORS_ONLN
- return sysconf (_SC_NPROCESSORS_ONLN);
- #else
- return gomp_icv (false)->nthreads_var;
- #endif
- }
- /* 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, nthreads_var = gomp_icv (false)->nthreads_var;
- n_onln = get_num_procs ();
- if (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)
- {
- return get_num_procs ();
- }
- ialias (omp_get_num_procs)
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