It has been found that during heavy network creation by Neutron (>1K
networks) dnsmasq is unable to complete due to lack of inotify user
instances.
Each neutron network spawns one dnsmasq process. Each dnsmasq process
consumes one inotify instance. Existing processes in network nodes consume
less than 10 inotify instances so this number would virtually be the
maximum number of networks supported.
For now we are setting this number to 8192 which will support over 8k
networks.
(cherry picked from commit 1f774fdeddbb3f059820ec6a9f0e18f3bb1adb85)
matelakat
commented
6 years ago 
It has been found that during heavy network creation by Neutron (>1K networks) dnsmasq is unable to complete due to lack of inotify user instances.
Each neutron network spawns one dnsmasq process. Each dnsmasq process consumes one inotify instance. Existing processes in network nodes consume less than 10 inotify instances so this number would virtually be the maximum number of networks supported.
For now we are setting this number to 8192 which will support over 8k networks.
(cherry picked from commit 1f774fdeddbb3f059820ec6a9f0e18f3bb1adb85)