spml/ucx: shuffle EPs creation

oshmem/mca/spml/ucx/spml_ucx.c

@@ -529,7 +529,7 @@ static int oshmem_shmem_xchng(
     if (NULL == rcv_sizes) {
         goto err;
     }
-   
+
     rc = oshmem_shmem_allgather(local_size, rcv_sizes, ucp_workers * sizeof(*rcv_sizes));
     if (MPI_SUCCESS != rc) {
         goto err;
@@ -634,16 +634,16 @@ int mca_spml_ucx_clear_put_op_mask(mca_spml_ucx_ctx_t *ctx)
 int mca_spml_ucx_add_procs(oshmem_group_t* group, size_t nprocs)
 {
     int rc                  = OSHMEM_ERROR;
-    int my_rank             = oshmem_my_proc_id();
     size_t ucp_workers      = mca_spml_ucx.ucp_workers;
     unsigned int *wk_roffs  = NULL;
     unsigned int *wk_rsizes = NULL;
     char *wk_raddrs         = NULL;
-    size_t i, w, n;
+    size_t i, j, w, n, temp;
     ucs_status_t err;
     ucp_address_t **wk_local_addr;
     unsigned int *wk_addr_len;
     ucp_ep_params_t ep_params;
+    int *indices;
 
     wk_local_addr = calloc(mca_spml_ucx.ucp_workers, sizeof(ucp_address_t *));
     wk_addr_len = calloc(mca_spml_ucx.ucp_workers, sizeof(size_t));
@@ -691,23 +691,40 @@ int mca_spml_ucx_add_procs(oshmem_group_t* group, size_t nprocs)
         }
     }
 
+    indices = malloc(nprocs * sizeof(int));
+    if (!indices) {
+        goto error;
+    }
+
+    for (i = 0; i < nprocs; i++) {
+        indices[i] = i;
+    }
+
+    srand((unsigned int)time(NULL));
+
     /* Get the EP connection requests for all the processes from modex */
-    for (n = 0; n < nprocs; ++n) {
-        i = (my_rank + n) % nprocs;
+    for (i = nprocs - 1; i >= 0; --i) {
+        /* Fisher-Yates shuffle algorithm */
+        if (i > 0) {
+            j = rand() % (i + 1);
+            temp = indices[i];
+            indices[i] = indices[j];
+            indices[j] = temp;
+        }
 
         ep_params.field_mask = UCP_EP_PARAM_FIELD_REMOTE_ADDRESS;
-        ep_params.address    = (ucp_address_t *)mca_spml_ucx.remote_addrs_tbl[0][i];
+        ep_params.address = (ucp_address_t *) mca_spml_ucx.remote_addrs_tbl[0][indices[i]];
 
         err = ucp_ep_create(mca_spml_ucx_ctx_default.ucp_worker[0], &ep_params,
-                &mca_spml_ucx_ctx_default.ucp_peers[i].ucp_conn);
+                            &mca_spml_ucx_ctx_default.ucp_peers[indices[i]].ucp_conn);
         if (UCS_OK != err) {
             SPML_UCX_ERROR("ucp_ep_create(proc=%zu/%zu) failed: %s", n, nprocs,
                     ucs_status_string(err));
             goto error2;
         }
 
         /* Initialize mkeys as NULL for all processes */
-        mca_spml_ucx_peer_mkey_cache_init(&mca_spml_ucx_ctx_default, i);
+        mca_spml_ucx_peer_mkey_cache_init(&mca_spml_ucx_ctx_default, indices[i]);
     }
 
     for (i = 0; i < mca_spml_ucx.ucp_workers; i++) {
@@ -719,6 +736,7 @@ int mca_spml_ucx_add_procs(oshmem_group_t* group, size_t nprocs)
     free(wk_roffs);
     free(wk_addr_len);
     free(wk_local_addr);
+    free(indices);
 
     SPML_UCX_VERBOSE(50, "*** ADDED PROCS ***");
 
@@ -753,6 +771,7 @@ int mca_spml_ucx_add_procs(oshmem_group_t* group, size_t nprocs)
     free(wk_raddrs);
     free(wk_rsizes);
     free(wk_roffs);
+    free(indices);
 error:
     free(wk_addr_len);
     free(wk_local_addr);
@@ -1025,7 +1044,7 @@ static inline void _ctx_remove(mca_spml_ucx_ctx_array_t *array, mca_spml_ucx_ctx
 
     opal_atomic_wmb ();
 }
-
+      
 static int mca_spml_ucx_ctx_create_common(long options, mca_spml_ucx_ctx_t **ucx_ctx_p)
 {
     ucp_worker_params_t params;
@@ -1044,7 +1063,7 @@ static int mca_spml_ucx_ctx_create_common(long options, mca_spml_ucx_ctx_t **ucx
     ucx_ctx->ucp_worker = calloc(1, sizeof(ucp_worker_h));
     ucx_ctx->ucp_workers = 1;
     ucx_ctx->synchronized_quiet = mca_spml_ucx_ctx_default.synchronized_quiet;
-    ucx_ctx->strong_sync = mca_spml_ucx_ctx_default.strong_sync;      
+    ucx_ctx->strong_sync = mca_spml_ucx_ctx_default.strong_sync;
 
     params.field_mask  = UCP_WORKER_PARAM_FIELD_THREAD_MODE;
     if (oshmem_mpi_thread_provided == SHMEM_THREAD_SINGLE ||