Fixes trac:2776. Let the openib BTL auto-detect its bandwidth.

cmr:v1.5.4

This commit was SVN r24621.

The following Trac tickets were found above:
  Ticket 2776 --> https://svn.open-mpi.org/trac/ompi/ticket/2776

ompi/mca/btl/base/btl_base_mca.c

@@ -109,7 +109,7 @@ int mca_btl_base_param_register(mca_base_component_t *version,
     }
 
     REG_INT("bandwidth", "Approximate maximum bandwidth of interconnect"
-            "(must be >= 1)", module->btl_bandwidth, 1, uint32_t);
+            "(0 = auto-detect value at run-time [not supported in all BTL modules], >= 1 = bandwidth in Mbps)", module->btl_bandwidth, 0, uint32_t);
 
     REG_INT("latency", "Approximate latency of interconnect (must be >= 0)",
             module->btl_latency, 0, uint32_t);

ompi/mca/btl/openib/btl_openib_mca.c

@@ -541,8 +541,9 @@ int btl_openib_register_mca_params(void)
 #if BTL_OPENIB_FAILOVER_ENABLED
     mca_btl_openib_module.super.btl_flags |= MCA_BTL_FLAGS_FAILOVER_SUPPORT;
 #endif
-    mca_btl_openib_module.super.btl_bandwidth = 800;
-    mca_btl_openib_module.super.btl_latency = 10;
+    /* Default to bandwidth auto-detection */
+    mca_btl_openib_module.super.btl_bandwidth = 0;
+    mca_btl_openib_module.super.btl_latency = 4;
     CHECK(mca_btl_base_param_register(
             &mca_btl_openib_component.super.btl_version,
             &mca_btl_openib_module.super));