libgomp/config/linux/affinity.c

   1 /* Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011
   2    Free Software Foundation, Inc.
   3    Contributed by Jakub Jelinek <jakub@redhat.com>.
   4
   5    This file is part of the GNU OpenMP Library (libgomp).
   6
   7    Libgomp is free software; you can redistribute it and/or modify it
   8    under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3, or (at your option)
  10    any later version.
  11
  12    Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
  13    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  14    FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  15    more details.
  16
  17    Under Section 7 of GPL version 3, you are granted additional
  18    permissions described in the GCC Runtime Library Exception, version
  19    3.1, as published by the Free Software Foundation.
  20
  21    You should have received a copy of the GNU General Public License and
  22    a copy of the GCC Runtime Library Exception along with this program;
  23    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24    <http://www.gnu.org/licenses/>.  */
  25
  26 /* This is a Linux specific implementation of a CPU affinity setting.  */
  27
  28 #ifndef _GNU_SOURCE
  29 #define _GNU_SOURCE 1
  30 #endif
  31 #include "libgomp.h"
  32 #include "proc.h"
  33 #include <stdlib.h>
  34 #include <unistd.h>
  35
  36 #ifdef HAVE_PTHREAD_AFFINITY_NP
  37
  38 static unsigned int affinity_counter;
  39
  40 void
  41 gomp_init_affinity (void)
  42 {
  43   cpu_set_t cpuset, cpusetnew;
  44   size_t idx, widx;
  45   unsigned long cpus = 0;
  46
  47   if (pthread_getaffinity_np (pthread_self (), sizeof (cpuset), &cpuset))
  48     {
  49       gomp_error ("could not get CPU affinity set");
  50       free (gomp_cpu_affinity);
  51       gomp_cpu_affinity = NULL;
  52       gomp_cpu_affinity_len = 0;
  53       return;
  54     }
  55
  56   CPU_ZERO (&cpusetnew);
  57   if (gomp_cpu_affinity_len == 0)
  58     {
  59       unsigned long count = gomp_cpuset_popcount (&cpuset);
  60       if (count >= 65536)
  61         count = 65536;
  62       gomp_cpu_affinity = malloc (count * sizeof (unsigned short));
  63       if (gomp_cpu_affinity == NULL)
  64         {
  65           gomp_error ("not enough memory to store CPU affinity list");
  66           return;
  67         }
  68       for (widx = idx = 0; widx < count && idx < 65536; idx++)
  69         if (CPU_ISSET (idx, &cpuset))
  70           {
  71             cpus++;
  72             gomp_cpu_affinity[widx++] = idx;
  73           }
  74     }
  75   else
  76     for (widx = idx = 0; idx < gomp_cpu_affinity_len; idx++)
  77       if (gomp_cpu_affinity[idx] < CPU_SETSIZE
  78           && CPU_ISSET (gomp_cpu_affinity[idx], &cpuset))
  79         {
  80           if (! CPU_ISSET (gomp_cpu_affinity[idx], &cpusetnew))
  81             {
  82               cpus++;
  83               CPU_SET (gomp_cpu_affinity[idx], &cpusetnew);
  84             }
  85           gomp_cpu_affinity[widx++] = gomp_cpu_affinity[idx];
  86         }
  87
  88   if (widx == 0)
  89     {
  90       gomp_error ("no CPUs left for affinity setting");
  91       free (gomp_cpu_affinity);
  92       gomp_cpu_affinity = NULL;
  93       gomp_cpu_affinity_len = 0;
  94       return;
  95     }
  96
  97   gomp_cpu_affinity_len = widx;
  98   if (cpus < gomp_available_cpus)
  99     gomp_available_cpus = cpus;
 100   CPU_ZERO (&cpuset);
 101   CPU_SET (gomp_cpu_affinity[0], &cpuset);
 102   pthread_setaffinity_np (pthread_self (), sizeof (cpuset), &cpuset);
 103   affinity_counter = 1;
 104 }
 105
 106 void
 107 gomp_init_thread_affinity (pthread_attr_t *attr)
 108 {
 109   unsigned int cpu;
 110   cpu_set_t cpuset;
 111
 112   cpu = __atomic_fetch_add (&affinity_counter, 1, MEMMODEL_RELAXED);
 113   cpu %= gomp_cpu_affinity_len;
 114   CPU_ZERO (&cpuset);
 115   CPU_SET (gomp_cpu_affinity[cpu], &cpuset);
 116   pthread_attr_setaffinity_np (attr, sizeof (cpu_set_t), &cpuset);
 117 }
 118
 119 #else
 120
 121 #include "../posix/affinity.c"
 122
 123 #endif