Add a new MCA parameter: mpi_keep_peer_hostnames. If this is nonzero,

(which is currently the default, although we may argue over this later
:-) ), a new field in the ompi_proc_t named proc_hostname will have
the string hostname of that peer.  If 0, this field will be NULL.

This allows for printing nicer error messages in environments where
peer hostnames are not otherwise easily obtainable, such as the mvapi
BTL (requested by Sandia, who has both a *huge* number of nodes and
6GB of RAM per node, so they don't care about the extra memory usage
;-) ).

This commit was SVN r9902.

ompi/proc/proc.c

@@ -9,6 +9,7 @@
  *                         University of Stuttgart.  All rights reserved.
  * Copyright (c) 2004-2006 The Regents of the University of California.
  *                         All rights reserved.
+ * Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
  * $COPYRIGHT$
  *
  * Additional copyrights may follow
@@ -33,6 +34,7 @@
 #include "ompi/mca/pml/pml.h"
 #include "ompi/datatype/dt_arch.h"
 #include "ompi/datatype/convertor.h"
+#include "ompi/runtime/params.h"
 
 static opal_list_t  ompi_proc_list;
 static opal_mutex_t ompi_proc_lock;
@@ -67,6 +69,10 @@ void ompi_proc_construct(ompi_proc_t* proc)
 
     proc->proc_flags = 0;
 
+    /* By default, put NULL in the hostname.  It may or may not get
+       filled in later -- consumer of this field beware! */
+    proc->proc_hostname = NULL;
+
     OPAL_THREAD_LOCK(&ompi_proc_lock);
     opal_list_append(&ompi_proc_list, (opal_list_item_t*)proc);
     OPAL_THREAD_UNLOCK(&ompi_proc_lock);
@@ -84,6 +90,9 @@ void ompi_proc_destruct(ompi_proc_t* proc)
      * destroyed here. It will be destroyed later when the ompi_ddt_finalize is called.
      */
     OBJ_RELEASE( proc->proc_convertor );
+    if (NULL != proc->proc_hostname) {
+        free(proc->proc_hostname);
+    }
     OPAL_THREAD_LOCK(&ompi_proc_lock);
     opal_list_remove_item(&ompi_proc_list, (opal_list_item_t*)proc);
     OPAL_THREAD_UNLOCK(&ompi_proc_lock);
@@ -535,6 +544,11 @@ static void callback(orte_gpr_notify_data_t *data, void *cbdata)
                             proc->proc_convertor = ompi_convertor_create(proc->proc_arch, 0);
                         }
 
+                        /* Save the hostname */
+                        if (ompi_mpi_keep_peer_hostnames) {
+                            proc->proc_hostname = str;
+                            str = NULL;
+                        }
                     }
                 }
             }

ompi/proc/proc.h

@@ -9,6 +9,7 @@
  *                         University of Stuttgart.  All rights reserved.
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
+ * Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
  * $COPYRIGHT$
  * 
  * Additional copyrights may follow
@@ -46,6 +47,8 @@ struct ompi_proc_t {
     struct ompi_convertor_t*  proc_convertor;
     /** process-wide lock */
     opal_mutex_t              proc_lock;
+    /** Keep the hostname around for debugging purposes */
+    char *proc_hostname;
     /** flags for this proc */
     uint8_t                   proc_flags;
 };

ompi/runtime/ompi_mpi_params.c

@@ -46,6 +46,8 @@ char *ompi_mpi_show_mca_params_file = NULL;
 bool ompi_mpi_paffinity_alone = false;
 bool ompi_mpi_abort_print_stack = false;
 int ompi_mpi_abort_delay = 0;
+bool ompi_mpi_keep_peer_hostnames = true;
+
 
 int ompi_mpi_register_params(void)
 {
@@ -138,6 +140,14 @@ int ompi_mpi_register_params(void)
                                 true, false, 
                                 -1, NULL);
 
+    /* Do we want to save hostnames for debugging messages?  This can
+       eat quite a bit of memory... */
+
+    mca_base_param_reg_int_name("mpi", "keep_peer_hostnames",
+                                "If nonzero, save the string hostnames of all MPI peer processes (mostly for error / debugging output messages).  This can add quite a bit of memory usage to each MPI process.",
+                                false, false, 1, &value);
+    ompi_mpi_keep_peer_hostnames = (bool) value;
+
     /* MPI_ABORT controls */
 
     mca_base_param_reg_int_name("mpi", "abort_delay",

ompi/runtime/params.h

@@ -89,6 +89,12 @@ OMPI_DECLSPEC extern char * ompi_mpi_show_mca_params_file;
  */
 OMPI_DECLSPEC extern bool ompi_mpi_paffinity_alone;
 
+    /**
+     * Whether we should keep the string hostnames of all the MPI
+     * process peers around or not (eats up a good bit of memory).
+     */
+    OMPI_DECLSPEC extern bool ompi_mpi_keep_peer_hostnames;
+
     /**
      * Whether an MPI_ABORT should print out a stack trace or not.
      */