Refs trac:853

Add new function opal_get_num_processors() that will return the number
of processors on the local host.  Does the Right thing in POSIX
environments (to include a special case for OS X), and will shortly do
the Right Thing for Windows (this commit includes a change to
configure, so I wanted to get that in before the US workday -- the
Windows code can some shortly because it won't involve configury
changes).

This commit was SVN r13506.

The following Trac tickets were found above:
  Ticket 853 --> https://svn.open-mpi.org/trac/ompi/ticket/853

configure.ac

@@ -583,7 +583,7 @@ AC_CHECK_HEADERS([alloca.h aio.h arpa/inet.h dirent.h \
     sys/resource.h sys/select.h sys/socket.h sys/sockio.h \
     stdarg.h sys/stat.h sys/statvfs.h sys/time.h sys/tree.h \
     sys/types.h sys/uio.h sys/utsname.h sys/wait.h syslog.h \
-    time.h termios.h ulimit.h unistd.h util.h utmp.h malloc.h])
+    time.h termios.h ulimit.h unistd.h util.h utmp.h malloc.h sys/sysctl.h])
 
 # Needed to work around Darwin requiring sys/socket.h for
 # net/if.h
@@ -713,7 +713,7 @@ OMPI_CHECK_FUNC_LIB([dirname], [gen])
 # Darwin doesn't need -lm, as it's a symlink to libSystem.dylib
 OMPI_CHECK_FUNC_LIB([ceil], [m])
 
-AC_CHECK_FUNCS([asprintf snprintf vasprintf vsnprintf openpty isatty htonl ntohl htons ntohs getpwuid fork waitpid execve pipe ptsname setsid mmap mallopt tcgetpgrp posix_memalign strsignal])
+AC_CHECK_FUNCS([asprintf snprintf vasprintf vsnprintf openpty isatty htonl ntohl htons ntohs getpwuid fork waitpid execve pipe ptsname setsid mmap mallopt tcgetpgrp posix_memalign strsignal sysconf])
 
 #
 # Make sure we can copy va_lists (need check declared, not linkable)
@@ -809,6 +809,18 @@ if test "$MPI_OFFSET_DATATYPE" = "not found"; then
 fi
 AC_DEFINE_UNQUOTED(OMPI_OFFSET_DATATYPE, $MPI_OFFSET_DATATYPE, [MPI datatype corresponding to MPI_Offset])
 
+# Do we have _SC_NPROCESSORS_ONLN? (only going to pass if we also have
+# <unistd.h> and sysconf(), which is ok) OS X 10.4 has <unistd.h> and
+# sysconf(), but does not have _SC_NPROCESSORS_ONLN.  Doh!
+
+AC_MSG_CHECKING([for _SC_NPROCESSORS_ONLN])
+AC_TRY_COMPILE([#include <unistd.h>],
+    [(void)sysconf(_SC_NPROCESSORS_ONLN);],
+[MSG=yes VALUE=1], [MSG=no VALUE=0])
+AC_DEFINE_UNQUOTED(OPAL_HAVE__SC_NPROCESSORS_ONLN, $VALUE,
+    [Whether we have the _SC_NPROCESSORS_ONLN])
+AC_MSG_RESULT([$MSG])
+
 # all: endian
 
 AC_C_BIGENDIAN

ompi/runtime/ompi_mpi_init.c

@@ -35,6 +35,7 @@
 #include "opal/threads/threads.h"
 #include "opal/util/show_help.h"
 #include "opal/util/stacktrace.h"
+#include "opal/util/num_procs.h"
 #include "opal/runtime/opal.h"
 #include "opal/event/event.h"
 
@@ -679,7 +680,7 @@ int ompi_mpi_init(int argc, char **argv, int requested, int *provided)
          * first, get the number of processors - if we can't then
          * we can't do anything but set conservative values
          */
-        if (OPAL_SUCCESS == opal_paffinity_base_get_num_processors(&num_processors)) {
+        if (OPAL_SUCCESS == opal_get_num_processors(&num_processors)) {
             /* got the num_processors - compare that to the number of
              * local procs in this job to decide if we are oversubscribed
              */

opal/util/Makefile.am

@@ -9,6 +9,7 @@
 #                         University of Stuttgart.  All rights reserved.
 # Copyright (c) 2004-2005 The Regents of the University of California.
 #                         All rights reserved.
+# Copyright (c) 2007      Cisco Systems, Inc.  All rights reserved.
 # $COPYRIGHT$
 #
 # Additional copyrights may follow
@@ -39,6 +40,7 @@ headers = \
 	keyval_parse.h \
         malloc.h \
         numtostr.h \
+        num_procs.h \
         opal_environ.h \
         os_dirpath.h \
         os_path.h \
@@ -68,6 +70,7 @@ libopalutil_la_SOURCES = \
 	keyval_parse.c \
         malloc.c \
         numtostr.c \
+        num_procs.c \
         opal_environ.c \
         os_dirpath.c \
         os_path.c \

opal/util/num_procs.c

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2007 The University of Tennessee and The University
+ *                    of Tennessee Research Foundation.  All rights
+ *                    reserved.
+ * Copyright (c) 2007 Cisco Systems, Inc.  All rights reserved.
+ * $COPYRIGHT$
+ * 
+ * Additional copyrights may follow
+ * 
+ * $HEADER$
+ */
+
+#include "opal_config.h"
+
+#include <unistd.h>
+
+#include "opal/constants.h"
+#include "opal/util/num_procs.h"
+#if defined(HAVE_SYS_SYSCTL_H)
+#include <sys/sysctl.h>
+#endif
+
+
+/*
+ * Simple wrapper to get the number of processors on the local host
+ */
+int opal_get_num_processors(int *num_procs)
+{
+#ifdef __WINDOWS__
+    /* Need to get the Right code for Windows... */
+    return OPAL_ERR_NOT_IMPLEMENTED;
+#else
+    /* POSIX environments */
+
+#if defined(__APPLE__)
+    /* OSX has a special function for this */
+    size_t size = sizeof(*num_procs) ;
+
+    if (0 == sysctlbyname( "hw.ncpu", num_procs, &size, NULL, 0)) {
+        return OPAL_SUCCESS;
+    }
+#elif OPAL_HAVE__SC_NPROCESSORS_ONLN
+    /* Other POSIX'es can use sysconf() */
+    int count = sysconf(_SC_NPROCESSORS_ONLN);
+    if (-1 != count) {
+        *num_procs = count;
+        return OPAL_SUCCESS;
+    }
+#endif
+    /* Default case if we don't know how to get the processor number or if
+       something fails. */
+    return OPAL_ERR_NOT_FOUND;
+#endif
+}

opal/util/num_procs.h

@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2007 Cisco Systems, Inc.  All rights reserved.
+ * $COPYRIGHT$
+ * 
+ * Additional copyrights may follow
+ * 
+ * $HEADER$
+ */
+
+/**
+ * @file
+ *
+ * This function is a simple wrapper to have an OS-independent
+ * mechanism to get the number of processors on a local host.
+ */
+
+#ifndef OPAL_NUM_PROCS_H
+#define OPAL_NUM_PROCS_H
+
+#include "opal_config.h"
+
+#if defined(c_plusplus) || defined(__cplusplus)
+extern "C" {
+#endif
+
+    /**
+     * Provide a portable method for getting the number of processors on
+     * the local machine.  In POSIX environments, this is a simple wrapper
+     * around sysconf().
+     *
+     * @retval OPAL_SUCCESS If successful, indicating that num_procs
+     * has a meaningful value.
+     * @retval OPAL_ERR_NOT_IMPLEMENTED on platforms that are not yet
+     * supported.
+     */
+    int opal_get_num_processors(int *num_procs);
+
+#if defined(c_plusplus) || defined(__cplusplus)
+}
+#endif
+
+#endif