| /* Copyright (C) 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc. |
| Contributed by Jakub Jelinek <jakub@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. */ |
| |
| #ifndef _GNU_SOURCE |
| #define _GNU_SOURCE 1 |
| #endif |
| #include "libgomp.h" |
| #include <sched.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 |
| static unsigned long |
| cpuset_popcount (cpu_set_t *cpusetp) |
| { |
| #ifdef CPU_COUNT |
| /* glibc 2.6 and above provide a macro for this. */ |
| return CPU_COUNT (cpusetp); |
| #else |
| size_t i; |
| unsigned long ret = 0; |
| extern int check[sizeof (cpusetp->__bits[0]) == sizeof (unsigned long int)]; |
| |
| (void) check; |
| for (i = 0; i < sizeof (*cpusetp) / 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 |
| cpu_set_t cpuset; |
| |
| if (pthread_getaffinity_np (pthread_self (), sizeof (cpuset), &cpuset) == 0) |
| { |
| /* Count only the CPUs this process can use. */ |
| gomp_global_icv.nthreads_var = cpuset_popcount (&cpuset); |
| if (gomp_global_icv.nthreads_var == 0) |
| gomp_global_icv.nthreads_var = 1; |
| return; |
| } |
| #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 |
| cpu_set_t cpuset; |
| |
| if (gomp_cpu_affinity == NULL) |
| { |
| /* Count only the CPUs this process can use. */ |
| if (pthread_getaffinity_np (pthread_self (), sizeof (cpuset), |
| &cpuset) == 0) |
| { |
| int ret = cpuset_popcount (&cpuset); |
| return ret != 0 ? ret : 1; |
| } |
| } |
| else |
| { |
| size_t idx; |
| static int affinity_cpus; |
| |
| /* 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. */ |
| CPU_ZERO (&cpuset); |
| if (affinity_cpus == 0) |
| { |
| int cpus = 0; |
| for (idx = 0; idx < gomp_cpu_affinity_len; idx++) |
| if (! CPU_ISSET (gomp_cpu_affinity[idx], &cpuset)) |
| { |
| cpus++; |
| CPU_SET (gomp_cpu_affinity[idx], &cpuset); |
| } |
| affinity_cpus = cpus; |
| } |
| return affinity_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) |