mpirun: add cli option to turn off gpu support

idea is that maybe one might want to build open mpi with gpu support,
but there may be performance benefit of disabling all gpu related
paths when using this library on systems without accelerators.

Signed-off-by: Howard Pritchard <howardp@lanl.gov>

Author: hppritcha

src/mca/schizo/ompi/schizo-ompi-cli.rstxt

@@ -163,6 +163,8 @@ MPI Options
   attached to predefined communicators during the first MPI call.
 * ``--memory-alloc-kinds``: Value is a comma separated list of
    memory allocation kinds.
+* ``--disable-gpu-support``: Specify to disable any accelerator support
+  built in to the Open MPI installation at run time.
 * ``--display-comm``: Display table of communication methods between
   MPI_COMM_WORLD ranks during MPI_Init
 * ``--display-comm-finalize``: Display table of communication methods

src/mca/schizo/ompi/schizo_ompi.c

@@ -19,7 +19,7 @@
  *                         and Technology (RIST). All rights reserved.
  * Copyright (c) 2018-2022 IBM Corporation.  All rights reserved.
  * Copyright (c) 2021-2024 Nanook Consulting  All rights reserved.
- * Copyright (c) 2022-2024 Triad National Security, LLC. All rights
+ * Copyright (c) 2022-2025 Triad National Security, LLC. All rights
  *                         reserved.
  * $COPYRIGHT$
  *
@@ -194,6 +194,7 @@ static struct option ompioptions[] = {
     PMIX_OPTION_DEFINE(PRTE_CLI_DISABLE_RECOVERY, PMIX_ARG_NONE),
     PMIX_OPTION_DEFINE(PRTE_CLI_CONTINUOUS, PMIX_ARG_NONE),
     PMIX_OPTION_DEFINE("with-ft", PMIX_ARG_REQD),
+    PMIX_OPTION_DEFINE("disable-gpu-support", PMIX_ARG_NONE),
 
     /* mpiexec mandated form launch key parameters - MPI 4.0 */
     PMIX_OPTION_DEFINE("initial-errhandler", PMIX_ARG_REQD),
@@ -1612,6 +1613,15 @@ static int parse_env(char **srcenv, char ***dstenv,
         }
     }
 
+   if (NULL != (opt = pmix_cmd_line_get_param(results, "disable-gpu-support"))) {
+        rc = check_cache(&cache, &cachevals, "disable_gpu_support", "true");
+        if (PRTE_SUCCESS != rc) {
+            PMIX_ARGV_FREE_COMPAT(cache);
+            PMIX_ARGV_FREE_COMPAT(cachevals);
+            return rc;
+        }
+    }
+
     if (pmix_cmd_line_is_taken(results, "display-comm") &&
         pmix_cmd_line_is_taken(results, "display-comm-finalize")) {
         PMIX_SETENV_COMPAT("OMPI_MCA_ompi_display_comm", "mpi_init,mpi_finalize", true, dstenv);