Why does openvswitch fail to start during overcloud deployments with dpdk and large amount of hugepages?

Issue

• Overcloud deployment fails after systemd fails to start openvswitch service.

Jan 24 12:10:40 compute-1 os-collect-config: Traceback (most recent call last):
Jan 24 12:10:40 compute-1 os-collect-config: File "/usr/bin/os-net-config", line 10, in <module>
Jan 24 12:10:40 compute-1 os-collect-config: sys.exit(main())
Jan 24 12:10:40 compute-1 os-collect-config: File "/usr/lib/python2.7/site-packages/os_net_config/cli.py", line 187, in main
Jan 24 12:10:40 compute-1 systemd: ovs-vswitchd.service failed.
Jan 24 12:10:40 compute-1 os-collect-config: activate=not opts.no_activate)
Jan 24 12:10:40 compute-1 os-collect-config: File "/usr/lib/python2.7/site-packages/os_net_config/impl_ifcfg.py", line 941, in apply
Jan 24 12:10:40 compute-1 os-collect-config: 'restart', 'openvswitch')
Jan 24 12:10:40 compute-1 os-collect-config: File "/usr/lib/python2.7/site-packages/os_net_config/__init__.py", line 224, in execute
Jan 24 12:10:40 compute-1 os-collect-config: processutils.execute(cmd, *args, **kwargs)
Jan 24 12:10:40 compute-1 os-collect-config: File "/usr/lib/python2.7/site-packages/oslo_concurrency/processutils.py", line 394, in execute
Jan 24 12:10:40 compute-1 os-collect-config: cmd=sanitized_cmd)
Jan 24 12:10:40 compute-1 os-collect-config: oslo_concurrency.processutils.ProcessExecutionError: Unexpected error while running command.
Jan 24 12:10:40 compute-1 os-collect-config: Command: /usr/bin/systemctl restart openvswitch
Jan 24 12:10:40 compute-1 os-collect-config: Exit code: 1
Jan 24 12:10:40 compute-1 os-collect-config: Stdout: u''
Jan 24 12:10:40 compute-1 os-collect-config: Stderr: u"A dependency job for openvswitch.service failed. See 'journalctl -xe' for details.\n"
Jan 24 12:10:40 compute-1 os-collect-config: + RETVAL=1
Jan 24 12:10:40 compute-1 os-collect-config: + [[ 1 == 2 ]]
Jan 24 12:10:40 compute-1 os-collect-config: + [[ 1 != 0 ]]
Jan 24 12:10:40 compute-1 os-collect-config: + echo 'ERROR: os-net-config configuration failed.'
Jan 24 12:10:40 compute-1 os-collect-config: ERROR: os-net-config configuration failed.
Jan 24 12:10:40 compute-1 os-collect-config: + exit 1

• openvswitch systemd script fails to start when dpdk is configured and more that 200GB hugepages are present on compute nodes.
  This issue is noticed irrespective of how much hugepages openvswitch is configured via '--socket-mem' .