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/* Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010

   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

    {

      /* 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)