Merge ~rodsmith/maas-cert-server:set-mtu-in-start-iperf3 into maas-cert-server:master

[Rod Smith]

Update start-iperf3 to have it set an MTU of 9000 on any NIC with an over-10Gbps speed on which iperf3 is launched.

Update start-iperf3 to have it set an MTU of 9000 on any NIC with an over-10Gbps speed on which iperf3 is launched.

[Jeff Lane  (bladernr)]

LGTM, thanks!

review: Approve

diff --git a/debian/changelog b/debian/changelog
index b2fdba6..346c710 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,10 @@
+maas-cert-server (0.4.8-0ppa1) bionic; urgency=medium
+
+  * Updated start-iperf3 script to ensure an MTU of 9000 is set on
+    any NIC with a speed of over 10 Gbps.
+
+ -- Rod Smith <[e-mail]>  Tue, 03 Mar 2020 10:10:51 -0500
+
 maas-cert-server (0.4.7-0ppa1) bionic; urgency=medium
 
   * Update maniacs-setup.sh to replace deprecated maas-region-admin call
diff --git a/usr/sbin/start-iperf3 b/usr/sbin/start-iperf3
index 419fa88..c3f819c 100755
--- a/usr/sbin/start-iperf3
+++ b/usr/sbin/start-iperf3
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 
-# Copyright (c) 2018 Canonical, Ltd.
+# Copyright (c) 2018-2020 Canonical, Ltd.
 #
 # Authors
 #   Rod Smith <[e-mail]>
@@ -128,6 +128,23 @@ def launch_all_iperf3(core_list, ip_address, num_instances):
             print("Failed running iperf: {}".format(iperf_exception.output))
 
 
+def set_mtu(device):
+    speed = psutil.net_if_stats()[device].speed
+    mtu = psutil.net_if_stats()[device].mtu
+    if (speed > 10000) and (mtu < 9000):
+        print("Trying to set MTU on {} to 9000".format(device))
+        cmd = "sudo ip link set {} mtu 9000".format(device)
+        try:
+            check_output(shlex.split(cmd), universal_newlines=True)
+        except CalledProcessError as mtu_exception:
+            print("Failed setting MTU: {}".format(mtu_exception.output))
+    if (speed > 10000):
+        mtu = psutil.net_if_stats()[device].mtu
+        print("MTU on {} is now {}".format(device, mtu))
+        if (mtu < 9000):
+            print("*** INADEQUATE MTU ON {}! ***".format(device))
+
+
 def main(args):
     gopts = ArgumentParser()
     gopts.add_argument('-a', '--address', type=str,
@@ -143,6 +160,7 @@ def main(args):
     if device is not None:
         node = find_numa(device)
         core_list = find_cores(node)
+        set_mtu(device)
         launch_all_iperf3(core_list, args.address, args.num_instances)
     else:
         print("Could not find a network device associated with {}!\n".