DAOS-16484 test: Support mixed speeds when selecting a default interf…

…ace (#15050)

Allow selecting a default interface that is running at a different speed
on different hosts.  Primarily this is to support selecting the ib0
interface by default when the launch node has a slower ib0 interface
than the cluster hosts.

Signed-off-by: Phil Henderson <[email protected]>

src/tests/ftest/util/environment_utils.py

@@ -9,6 +9,7 @@
 
 from ClusterShell.NodeSet import NodeSet
 # pylint: disable=import-error,no-name-in-module
+from util.host_utils import get_local_host
 from util.network_utils import (PROVIDER_ALIAS, SUPPORTED_PROVIDERS, NetworkException,
                                 get_common_provider, get_fastest_interface)
 from util.run_utils import run_remote
@@ -326,7 +327,7 @@ def _default_interface(self, logger, hosts):
             # Find all the /sys/class/net interfaces on the launch node (excluding lo)
             logger.debug("Detecting network devices - D_INTERFACE not set")
             try:
-                interface = get_fastest_interface(logger, hosts)
+                interface = get_fastest_interface(logger, hosts | get_local_host())
             except NetworkException as error:
                 raise TestEnvironmentException("Error obtaining a default interface!") from error
         return interface

src/tests/ftest/util/network_utils.py

@@ -405,11 +405,12 @@ def get_fastest_interface(logger, hosts, verbose=True):
     for interface in common_interfaces:
         detected_speeds = get_interface_speeds(logger, hosts, interface, verbose)
         speed_list = []
+        speed_hosts = NodeSet()
         for speed, node_set in detected_speeds.items():
-            if node_set == hosts:
-                # Only include detected homogeneous interface speeds
-                speed_list.append(speed)
-        if speed_list:
+            speed_list.append(speed)
+            speed_hosts.add(node_set)
+        if speed_list and speed_hosts == hosts:
+            # Only include interface speeds if a speed is detected on all the hosts
             interface_speeds[interface] = min(speed_list)
 
     logger.info("Active network interface speeds on %s:", hosts)