osc/rdma: add an mca parameter to list MTLs for which osc pt2pt should have

higher priority than rdma and default to psm2.

Context: the Intel Omni-path driver (hfi1) has verbs support, so the openib
btl is available to use. However, at a bad performance. Without this
change osc rdma using btl openib is the default choice when running on Intel
Omni-path, with a lower performance than osc pt2pt over mtl psm2.

Signed-off-by: Matias A Cabral <matias.a.cabral@intel.com>

ompi/mca/osc/rdma/osc_rdma_component.c

@@ -15,7 +15,7 @@
  * Copyright (c) 2010      Oracle and/or its affiliates.  All rights reserved.
  * Copyright (c) 2012-2015 Sandia National Laboratories.  All rights reserved.
  * Copyright (c) 2015      NVIDIA Corporation.  All rights reserved.
- * Copyright (c) 2015      Intel, Inc. All rights reserved.
+ * Copyright (c) 2015-2017 Intel, Inc. All rights reserved.
  * Copyright (c) 2016-2017 IBM Corporation. All rights reserved.
  * $COPYRIGHT$
  *
@@ -55,6 +55,7 @@
 #include "opal/mca/btl/base/base.h"
 #include "opal/mca/base/mca_base_pvar.h"
 #include "ompi/mca/bml/base/base.h"
+#include "ompi/mca/mtl/base/base.h"
 
 static int ompi_osc_rdma_component_register (void);
 static int ompi_osc_rdma_component_init (bool enable_progress_threads, bool enable_mpi_threads);
@@ -70,10 +71,12 @@ static int ompi_osc_rdma_set_info (struct ompi_win_t *win, struct opal_info_t *i
 static int ompi_osc_rdma_get_info (struct ompi_win_t *win, struct opal_info_t **info_used);
 
 static int ompi_osc_rdma_query_btls (ompi_communicator_t *comm, struct mca_btl_base_module_t **btl);
+static int ompi_osc_rdma_query_mtls (void);
 
 static char* ompi_osc_rdma_set_no_lock_info(opal_infosubscriber_t *obj, char *key, char *value);
 
 static char *ompi_osc_rdma_btl_names;
+static char *ompi_osc_rdma_mtl_names;
 
 ompi_osc_rdma_component_t mca_osc_rdma_component = {
     .super = {
@@ -223,6 +226,13 @@ static int ompi_osc_rdma_component_register (void)
                                             MCA_BASE_VAR_TYPE_STRING, NULL, 0, 0, OPAL_INFO_LVL_3,
                                             MCA_BASE_VAR_SCOPE_GROUP, &ompi_osc_rdma_btl_names);
 
+    ompi_osc_rdma_mtl_names = "psm2";
+    (void) mca_base_component_var_register (&mca_osc_rdma_component.super.osc_version, "mtls",
+                                            "Comma-delimited list of MTL component names to lower the priority of rdma "
+                                            "osc component favoring pt2pt osc (default: psm2)",
+                                            MCA_BASE_VAR_TYPE_STRING, NULL, 0, 0, OPAL_INFO_LVL_3,
+                                            MCA_BASE_VAR_SCOPE_GROUP, &ompi_osc_rdma_mtl_names);
+
 
     /* register performance variables */
 
@@ -340,6 +350,10 @@ static int ompi_osc_rdma_component_query (struct ompi_win_t *win, void **base, s
     }
 #endif /* OPAL_CUDA_SUPPORT */
 
+    if (OMPI_SUCCESS == ompi_osc_rdma_query_mtls ()) {
+        return 5; /* this has to be lower that osc pt2pt default priority */
+    }
+
     if (OMPI_SUCCESS != ompi_osc_rdma_query_btls (comm, NULL)) {
         return -1;
     }
@@ -709,6 +723,21 @@ static int allocate_state_shared (ompi_osc_rdma_module_t *module, void **base, s
     return ret;
 }
 
+static int ompi_osc_rdma_query_mtls (void)
+{
+    char **mtls_to_use;
+
+    mtls_to_use = opal_argv_split (ompi_osc_rdma_mtl_names, ',');
+    if (mtls_to_use && ompi_mtl_base_selected_component) {
+	for (int i = 0 ; mtls_to_use[i] ; ++i) {
+	    if (0 == strcmp (mtls_to_use[i], ompi_mtl_base_selected_component->mtl_version.mca_component_name)) {
+		return OMPI_SUCCESS;
+	    }
+	}
+    }
+    return -1;
+}
+
 static int ompi_osc_rdma_query_btls (ompi_communicator_t *comm, struct mca_btl_base_module_t **btl)
 {
     struct mca_btl_base_module_t **possible_btls = NULL;