oshmem: Add symmetric key environment variable

Author: tvegas1

oshmem/mca/spml/ucx/spml_ucx.c

@@ -727,6 +727,10 @@ sshmem_mkey_t *mca_spml_ucx_register(void* addr,
         mem_map_params.length     = size;
         mem_map_params.flags      = flags;
 
+        if (mca_spml_ucx.symmetric_rkey) {
+            mem_map_params.flags |= UCP_MEM_MAP_SYMMETRIC_RKEY;
+        }
+
         status = ucp_mem_map(mca_spml_ucx.ucp_context, &mem_map_params, &mem_h);
         if (UCS_OK != status) {
             goto error_out;

oshmem/mca/spml/ucx/spml_ucx_component.c

@@ -153,6 +153,10 @@ static int mca_spml_ucx_component_register(void)
                                      "Enable asynchronous progress thread",
                                      &mca_spml_ucx.async_progress);
 
+    mca_spml_ucx_param_register_bool("symmetric_rkey", 0,
+                                     "Enable remote keys deduplication to save memory at scale (best-effort)",
+                                     &mca_spml_ucx.symmetric_rkey);
+
     mca_spml_ucx_param_register_int("async_tick_usec", 3000,
                                     "Asynchronous progress tick granularity (in usec)",
                                     &mca_spml_ucx.async_tick);

oshmem/mca/sshmem/ucx/sshmem_ucx_module.c

@@ -126,6 +126,10 @@ segment_create_internal(map_segment_t *ds_buf, void *address, size_t size,
     mem_map_params.length     = size;
     mem_map_params.flags      = flags;
 
+    if (spml->symmetric_rkey) {
+        mem_map_params.flags |= UCP_MEM_MAP_SYMMETRIC_RKEY;
+    }
+
     status = ucp_mem_map(spml->ucp_context, &mem_map_params, &mem_h);
     if (UCS_OK != status) {
         SSHMEM_ERROR("ucp_mem_map() failed: %s\n", ucs_status_string(status));