Coll/hcoll: don't init opal memhooks unless explicitely requested by user

    If user sets HCOLL_EXTERNAL_UCM_EVENTS=1 then we try init opal
    memory framework and register a mem release cb. Otherwise, rely on ucx.

Signed-off-by: Valentin Petrov <valentinp@mellanox.com>

Author: Valentin Petrov

ompi/mca/coll/hcoll/coll_hcoll_component.c

@@ -209,29 +209,10 @@ static int hcoll_open(void)
 {
     mca_coll_hcoll_component_t *cm;
     cm  = &mca_coll_hcoll_component;
-
     mca_coll_hcoll_output = opal_output_open(NULL);
     opal_output_set_verbosity(mca_coll_hcoll_output, cm->hcoll_verbose);
-
     hcoll_rte_fns_setup();
-
     cm->libhcoll_initialized = false;
-
-    (void)mca_base_framework_open(&opal_memory_base_framework, 0);
-
-    /* Register memory hooks */
-    if ((OPAL_MEMORY_FREE_SUPPORT | OPAL_MEMORY_MUNMAP_SUPPORT) ==
-        ((OPAL_MEMORY_FREE_SUPPORT | OPAL_MEMORY_MUNMAP_SUPPORT) &
-         opal_mem_hooks_support_level()))
-    {
-        setenv("MXM_HCOLL_MEM_ON_DEMAND_MAP", "y", 0);
-        HCOL_VERBOSE(1, "Enabling on-demand memory mapping");
-        cm->using_mem_hooks = 1;
-    } else {
-        HCOL_VERBOSE(1, "Disabling on-demand memory mapping");
-        cm->using_mem_hooks = 0;
-    }
-
     return OMPI_SUCCESS;
 }
 

ompi/mca/coll/hcoll/coll_hcoll_module.c

@@ -301,17 +301,28 @@ mca_coll_hcoll_comm_query(struct ompi_communicator_t *comm, int *priority)
             HCOL_ERROR("Hcol library init failed");
             return NULL;
         }
-
 #if HCOLL_API >= HCOLL_VERSION(3,2)
-        if (cm->using_mem_hooks && cm->init_opts->mem_hook_needed) {
+        if (cm->init_opts->mem_hook_needed) {
 #else
-        if (cm->using_mem_hooks && hcoll_check_mem_release_cb_needed()) {
+        if (hcoll_check_mem_release_cb_needed()) {
 #endif
-            opal_mem_hooks_register_release(mca_coll_hcoll_mem_release_cb, NULL);
+            rc = mca_base_framework_open(&opal_memory_base_framework, 0);
+            if (OPAL_SUCCESS != rc) {
+                HCOL_VERBOSE(1, "failed to initialize memory base framework: %d, "
+                             "memory hooks will not be used", rc);
+            } else {
+                if ((OPAL_MEMORY_FREE_SUPPORT | OPAL_MEMORY_MUNMAP_SUPPORT) ==
+                    ((OPAL_MEMORY_FREE_SUPPORT | OPAL_MEMORY_MUNMAP_SUPPORT) &
+                     opal_mem_hooks_support_level())) {
+                    HCOL_VERBOSE(1, "using OPAL memory hooks as external events");
+                    cm->using_mem_hooks = 1;
+                    opal_mem_hooks_register_release(mca_coll_hcoll_mem_release_cb, NULL);
+                    setenv("MXM_HCOLL_MEM_ON_DEMAND_MAP", "y", 0);
+                }
+            }
         } else {
             cm->using_mem_hooks = 0;
         }
-
         copy_fn.attr_communicator_copy_fn = (MPI_Comm_internal_copy_attr_function*) MPI_COMM_NULL_COPY_FN;
         del_fn.attr_communicator_delete_fn = hcoll_comm_attr_del_fn;
         err = ompi_attr_create_keyval(COMM_ATTR, copy_fn, del_fn, &hcoll_comm_attr_keyval, NULL ,0, NULL);