Don't use '-A' in network.py on non-numa systems (BugFix) (#711)

* Fix: In network.py, don't pass -A option to iperf3 if NUMA is unsupported

* add first tests for the network.py

---------

Co-authored-by: Maciej Kisielewski <maciej.kisielewski@canonical.com>

providers/base/bin/network.py

@@ -174,16 +174,15 @@ def find_numa(self, device):
             with open(filename, "r") as file:
                 node_num = int(file.read())
         except FileNotFoundError:
-            logging.warning("WARNING: Could not find the NUMA node "
-                            "associated with {}!".format(device))
-            logging.warning("Setting the association to NUMA node 0, "
-                            "which may not be optimal!")
-            node_num = 0
+            node_num = -1
         # Some systems (that don't support NUMA?) produce a node_num of -1.
-        # Change this to 0, which seems to be correct....
+        # Later in the script, this will be interpreted to omit the -A option
+        # to iperf3, thus disabling NUMA features.
         if node_num == -1:
-            node_num = 0
-        logging.info("NUMA node of {} is {}....".format(device, node_num))
+            logging.warning("WARNING: Could not find the NUMA node "
+                            "associated with {}!".format(device))
+        else:
+            logging.info("NUMA node of {} is {}....".format(device, node_num))
         return node_num
 
     def extract_core_list(self, line):
@@ -214,6 +213,9 @@ def find_cores(self, numa_node):
         """Return a list of CPU cores tied to the specified NUMA node."""
         numa_return = check_output("lscpu", universal_newlines=True,
                                    stderr=STDOUT).split("\n")
+        # Note: If numa_node = -1, the below will never find a match, so
+        # core_list will remain empty, and later in the script, the -A option
+        # to iperf3 will be dropped.
         expression = "NUMA node.*" + str(numa_node) + ".*CPU"
 
         regex = re.compile(expression)

providers/base/tests/test_network.py

@@ -0,0 +1,35 @@
+#!/usr/bin/env python3
+# Copyright 2024 Canonical Ltd.
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 3,
+# as published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import unittest
+from unittest.mock import patch, mock_open
+
+from network import IPerfPerformanceTest
+
+class IPerfPerfomanceTestTests(unittest.TestCase):
+
+    def test_find_numa_reports_node(self):
+        with patch('builtins.open', mock_open(read_data="1")) as mo:
+            returned = IPerfPerformanceTest.find_numa(None, "device")
+            self.assertEqual(returned, 1)
+
+    def test_find_numa_minus_one_from_sysfs(self):
+        with patch('builtins.open', mock_open(read_data="-1")) as mo:
+            returned = IPerfPerformanceTest.find_numa(None, "device")
+            self.assertEqual(returned, -1)
+    def test_find_numa_numa_node_not_found(self):
+        with patch('builtins.open', mock_open()) as mo:
+            mo.side_effect = FileNotFoundError
+            returned = IPerfPerformanceTest.find_numa(None, "device")
+            self.assertEqual(returned, -1)