tests/limit - Add a test verifying we can reach the new VIF limit of 16

Currently the test verifies that interfaces have been created correctly
(that there were enough grant frames to allocate all the queues), and
simply prints performance metrics. This should be integrated with
whatever database we are going to use for performance monitoring in the
future.

Signed-off-by: Andrii Sultanov <[email protected]>

Author: last-genius

tests/limits/__init__.py

@@ -0,0 +1,85 @@
+import ipaddress
+import os
+import pytest
+import logging
+
+# Requirements:
+# - one XCP-ng host (--host) >= 8.2
+# - a VM (--vm)
+
+vif_limit = 16
+interface_name = "enX"
+vcpus = '8'
+
+# There is a ResourceWarning due to background=True on an ssh call
+# We do ensure the processes are killed
+@pytest.mark.filterwarnings("ignore::ResourceWarning")
+@pytest.mark.debian_uefi_vm
+class TestVIFLimit:
+    def test_vif_limit(self, host, imported_vm):
+        vm = imported_vm
+        if (vm.is_running()):
+            logging.info("VM already running, shutting it down first")
+            vm.shutdown(verify=True)
+
+        network_uuid = vm.vifs()[0].param_get('network-uuid')
+        existing_vifs = len(vm.vifs())
+
+        logging.info('Give some more vCPUs (default is 1)')
+        vm.param_set('VCPUs-max', vcpus)
+        vm.param_set('VCPUs-at-startup', vcpus)
+
+        logging.info('Create VIFs before starting the VM')
+        for i in range(existing_vifs, vif_limit):
+            vm.create_vif(i, network_uuid=network_uuid)
+
+        vm.start()
+        vm.wait_for_os_booted()
+
+        logging.info('Verify the interfaces exist in the guest')
+        for i in range(0, vif_limit):
+            if vm.ssh_with_result([f'test -d /sys/class/net/{interface_name}{i}']).returncode != 0:
+                guest_error = vm.ssh_with_result(['dmesg | grep -B1 -A3 xen_netfront']).stdout
+                logging.error("dmesg:\n%s", guest_error)
+                assert False, "The interface does not exist in the guest, check dmesg output for errors"
+
+        logging.info('Configure interfaces')
+        config = '\n'.join([f'iface {interface_name}{i} inet dhcp\n'
+                            f'auto {interface_name}{i}'
+                            for i in range(1, vif_limit)])
+        vm.ssh([f'echo "{config}" >> /etc/network/interfaces'])
+
+        logging.info('Install iperf3 on VM and host')
+        if vm.ssh_with_result(['apt install iperf3 --assume-yes']).returncode != 0:
+            assert False, "Failed to install iperf3 on the VM"
+        host.yum_install(['iperf3'])
+
+        logging.info('Reconfigure VM networking')
+        if vm.ssh_with_result(['systemctl restart networking']).returncode != 0:
+            assert False, "Failed to configure networking"
+
+        # Test iperf on all interfaces in parallel
+        # Clean up on exceptions
+        try:
+            logging.info('Create separate iperf servers on the host')
+            host_script = [f'iperf3 -s -p {5100+i} &'
+                           for i in range(0, vif_limit)]
+            host_script = '\n'.join(host_script)
+            host.ssh([f'echo "{host_script}" > host_script'])
+            host.ssh(['nohup bash -c "bash host_script" < /dev/null &>/dev/null &'],
+                     background=True)
+
+            logging.info('Start multiple iperfs on separate interfaces on the VM')
+            vm_script = [f'iperf3 --no-delay -c {host.hostname_or_ip} '
+                         f'-p {5100+i} --bind-dev {interface_name}{i} '
+                         f'--interval 0 --parallel 1 --time 30 &'
+                         for i in range(0, vif_limit)]
+            vm_script = '\n'.join(vm_script)
+            vm.ssh([f'echo "{vm_script}" > vm_script'])
+            stdout = vm.ssh(['bash vm_script'])
+
+            # TODO: log this into some performance time series DB
+            logging.info(stdout)
+        finally:
+            vm.ssh(['kill -9 `pgrep iperf3` || true'])
+            host.ssh('killall iperf3')