path: root/lib/nproc.c

/* Detect the number of processors.

   Copyright (C) 2009 Free Software Foundation, Inc.

   This program 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 2, or (at your option)
   any later version.

   This program 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.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

/* Written by Glen Lenker and Bruno Haible.  */

#include <config.h>
#include "nproc.h"

#include <stdlib.h>
#include <unistd.h>

#if HAVE_PTHREAD_AFFINITY_NP && 0
# include <pthread.h>
# include <sched.h>
#endif
#if HAVE_SCHED_GETAFFINITY_LIKE_GLIBC || HAVE_SCHED_GETAFFINITY_NP
# include <sched.h>
#endif

#include <sys/types.h>

#if HAVE_SYS_PSTAT_H
# include <sys/pstat.h>
#endif

#if HAVE_SYS_SYSMP_H
# include <sys/sysmp.h>
#endif

#if HAVE_SYS_PARAM_H
# include <sys/param.h>
#endif

#if HAVE_SYS_SYSCTL_H
# include <sys/sysctl.h>
#endif

#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
# define WIN32_LEAN_AND_MEAN
# include <windows.h>
#endif

#include "c-ctype.h"

#define ARRAY_SIZE(a) (sizeof (a) / sizeof ((a)[0]))

unsigned long int
num_processors (enum nproc_query query)
{
  if (query == NPROC_CURRENT_OVERRIDABLE)
    {
      /* Test the environment variable OMP_NUM_THREADS, recognized also by all
         programs that are based on OpenMP.  The OpenMP spec says that the
         value assigned to the environment variable "may have leading and
         trailing white space". */
      const char *envvalue = getenv ("OMP_NUM_THREADS");

      if (envvalue != NULL)
        {
          while (*envvalue != '\0' && c_isspace (*envvalue))
            envvalue++;
          /* Convert it from decimal to 'unsigned long'.  */
          if (c_isdigit (*envvalue))
            {
              char *endptr = NULL;
              unsigned long int value = strtoul (envvalue, &endptr, 10);

              if (endptr != NULL)
                {
                  while (*endptr != '\0' && c_isspace (*endptr))
                    endptr++;
                  if (*endptr == '\0')
                    return (value > 0 ? value : 1);
                }
            }
        }

      query = NPROC_CURRENT;
    }
  /* Here query is one of NPROC_ALL, NPROC_CURRENT.  */

  if (query == NPROC_CURRENT)
    {
      /* glibc >= 2.3.3 with NPTL and NetBSD 5 have pthread_getaffinity_np,
         but with different APIs.  Also it requires linking with -lpthread.
         Therefore this code is not enabled.
         glibc >= 2.3.4 has sched_getaffinity whereas NetBSD 5 has
         sched_getaffinity_np.  */
#if HAVE_PTHREAD_AFFINITY_NP && defined __GLIBC__ && 0
      {
        cpu_set_t set;

        if (pthread_getaffinity_np (pthread_self (), sizeof (set), &set) == 0)
          {
            unsigned long count;

# ifdef CPU_COUNT
            /* glibc >= 2.6 has the CPU_COUNT macro.  */
            count = CPU_COUNT (&set);
# else
            size_t i;

            count = 0;
            for (i = 0; i < CPU_SETSIZE; i++)
              if (CPU_ISSET (i, &set))
                count++;
# endif
            if (count > 0)
              return count;
          }
      }
#elif HAVE_PTHREAD_AFFINITY_NP && defined __NetBSD__ && 0
      {
        cpuset_t *set;

        set = cpuset_create ();
        if (set != NULL)
          {
            unsigned long count = 0;

            if (pthread_getaffinity_np (pthread_self (), cpuset_size (set), set)
                == 0)
              {
                cpuid_t i;

                for (i = 0;; i++)
                  {
                    int ret = cpuset_isset (i, set);
                    if (ret < 0)
                      break;
                    if (ret > 0)
                      count++;
                  }
              }
            cpuset_destroy (set);
            if (count > 0)
              return count;
          }
      }
#elif HAVE_SCHED_GETAFFINITY_LIKE_GLIBC /* glibc >= 2.3.4 */
      {
        cpu_set_t set;

        if (sched_getaffinity (0, sizeof (set), &set) == 0)
          {
            unsigned long count;

# ifdef CPU_COUNT
            /* glibc >= 2.6 has the CPU_COUNT macro.  */
            count = CPU_COUNT (&set);
# else
            size_t i;

            count = 0;
            for (i = 0; i < CPU_SETSIZE; i++)
              if (CPU_ISSET (i, &set))
                count++;
# endif
            if (count > 0)
              return count;
          }
      }
#elif HAVE_SCHED_GETAFFINITY_NP /* NetBSD >= 5 */
      {
        cpuset_t *set;

        set = cpuset_create ();
        if (set != NULL)
          {
            unsigned long count = 0;

            if (sched_getaffinity_np (getpid (), cpuset_size (set), set) == 0)
              {
                cpuid_t i;

                for (i = 0;; i++)
                  {
                    int ret = cpuset_isset (i, set);
                    if (ret < 0)
                      break;
                    if (ret > 0)
                      count++;
                  }
              }
            cpuset_destroy (set);
            if (count > 0)
              return count;
          }
      }
#endif

#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
      { /* This works on native Windows platforms.  */
        DWORD_PTR process_mask;
        DWORD_PTR system_mask;

        if (GetProcessAffinityMask (GetCurrentProcess (),
                                    &process_mask, &system_mask))
          {
            DWORD_PTR mask = process_mask;
            unsigned long count = 0;

            for (; mask != 0; mask = mask >> 1)
              if (mask & 1)
                count++;
            if (count > 0)
              return count;
          }
      }
#endif

#if defined _SC_NPROCESSORS_ONLN
      { /* This works on glibc, MacOS X 10.5, FreeBSD, AIX, OSF/1, Solaris,
           Cygwin, Haiku.  */
        long int nprocs = sysconf (_SC_NPROCESSORS_ONLN);
        if (nprocs > 0)
          return nprocs;
      }
#endif
    }
  else /* query == NPROC_ALL */
    {
#if defined _SC_NPROCESSORS_CONF
      { /* This works on glibc, MacOS X 10.5, FreeBSD, AIX, OSF/1, Solaris,
           Cygwin, Haiku.  */
        long int nprocs = sysconf (_SC_NPROCESSORS_CONF);
        if (nprocs > 0)
          return nprocs;
      }
#endif
    }

#if HAVE_PSTAT_GETDYNAMIC
  { /* This works on HP-UX.  */
    struct pst_dynamic psd;
    if (pstat_getdynamic (&psd, sizeof psd, 1, 0) >= 0)
      {
        /* The field psd_proc_cnt contains the number of active processors.
           In newer releases of HP-UX 11, the field psd_max_proc_cnt includes
           deactivated processors.  */
        if (query == NPROC_CURRENT)
          {
            if (psd.psd_proc_cnt > 0)
              return psd.psd_proc_cnt;
          }
        else
          {
            if (psd.psd_max_proc_cnt > 0)
              return psd.psd_max_proc_cnt;
          }
      }
  }
#endif

#if HAVE_SYSMP && defined MP_NAPROCS && defined MP_NPROCS
  { /* This works on IRIX.  */
    /* MP_NPROCS yields the number of installed processors.
       MP_NAPROCS yields the number of processors available to unprivileged
       processes.  */
    int nprocs =
      sysmp (query == NPROC_CURRENT && getpid () != 0
             ? MP_NAPROCS
             : MP_NPROCS);
    if (nprocs > 0)
      return nprocs;
  }
#endif

  /* Finally, as fallback, use the APIs that don't distinguish between
     NPROC_CURRENT and NPROC_ALL.  */

#if HAVE_SYSCTL && defined HW_NCPU
  { /* This works on MacOS X, FreeBSD, NetBSD, OpenBSD.  */
    int nprocs;
    size_t len = sizeof (nprocs);
    static int mib[2] = { CTL_HW, HW_NCPU };

    if (sysctl (mib, ARRAY_SIZE (mib), &nprocs, &len, NULL, 0) == 0
        && len == sizeof (nprocs)
        && 0 < nprocs)
      return nprocs;
  }
#endif

#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  { /* This works on native Windows platforms.  */
    SYSTEM_INFO system_info;
    GetSystemInfo (&system_info);
    if (0 < system_info.dwNumberOfProcessors)
      return system_info.dwNumberOfProcessors;
  }
#endif

  return 1;
}