[neutron] DHCP agent event processing multithread LP#2070376

Hello Neutrinos:

As discussed during the last Neutron drivers meeting, I said that I was going to benchmark the performance of the DHCP agent with and without multiple event processing threads. The result is in [2]. As expected, the number of threads attending the received events (network creation, port deletion, etc) does not affect the speed of the DHCP agent. In particular I tested the resync transient that happens during the DHCP agent restart, that is easy to reproduce and provides consistent results.

Regards.

[1]https://bugs.launchpad.net/neutron/+bug/2070376 [2]https://bugs.launchpad.net/neutron/+bug/2070376/comments/1