Per f2f meeting: if async modex is given, default to no MPI init barrier, letting the user override that if desired.

Signed-off-by: Ralph Castain <rhc@open-mpi.org>

ompi/runtime/ompi_mpi_init.c

@@ -17,7 +17,7 @@
  * Copyright (c) 2008-2009 Sun Microsystems, Inc.  All rights reserved.
  * Copyright (c) 2011      Sandia National Laboratories. All rights reserved.
  * Copyright (c) 2012-2013 Inria.  All rights reserved.
- * Copyright (c) 2014-2016 Intel, Inc.  All rights reserved.
+ * Copyright (c) 2014-2017 Intel, Inc.  All rights reserved.
  * Copyright (c) 2014-2016 Research Organization for Information Science
  *                         and Technology (RIST). All rights reserved.
  * Copyright (c) 2016      Mellanox Technologies Ltd. All rights reserved.
@@ -640,10 +640,10 @@ int ompi_mpi_init(int argc, char **argv, int requested, int *provided)
      * if data exchange is required. The modex occurs solely across procs
      * in our job. If a barrier is required, the "modex" function will
      * perform it internally */
-    active = true;
     opal_pmix.commit();
     if (!opal_pmix_base_async_modex) {
         if (NULL != opal_pmix.fence_nb) {
+            active = true;
             opal_pmix.fence_nb(NULL, opal_pmix_collect_all_data,
                                fence_release, (void*)&active);
             OMPI_LAZY_WAIT_FOR_COMPLETION(active);

ompi/runtime/ompi_mpi_params.c

@@ -14,7 +14,7 @@
  * Copyright (c) 2007-2015 Los Alamos National Security, LLC.  All rights
  *                         reserved.
  * Copyright (c) 2013      NVIDIA Corporation.  All rights reserved.
- * Copyright (c) 2013-2016 Intel, Inc. All rights reserved
+ * Copyright (c) 2013-2017 Intel, Inc.  All rights reserved.
  * Copyright (c) 2015      Mellanox Technologies, Inc.
  *                         All rights reserved.
  * Copyright (c) 2016      Research Organization for Information Science
@@ -37,6 +37,7 @@
 #include "ompi/runtime/params.h"
 #include "ompi/mca/rte/rte.h"
 
+#include "opal/mca/pmix/base/base.h"
 #include "opal/util/argv.h"
 #include "opal/util/output.h"
 #include "opal/util/show_help.h"
@@ -286,7 +287,11 @@ int ompi_mpi_register_params(void)
                                  MCA_BASE_VAR_SCOPE_READONLY,
                                  &ompi_mpi_dynamics_enabled);
 
+    if (opal_pmix_base_async_modex) {
+        ompi_async_mpi_init = true;
+    } else {
         ompi_async_mpi_init = false;
+    }
     (void) mca_base_var_register("ompi", "async", "mpi", "init",
                                  "Do not perform a barrier at the end of MPI_Init",
                                  MCA_BASE_VAR_TYPE_BOOL, NULL, 0, 0,