tree e33489a267c08977d9ec01ad203a45e040dd8803
parent f0386ca40ed33bff3721765bb01f22f7b17805e6
author Oleg Bondarev <obondarev@mirantis.com> 1557904822 +0400
committer Oleg Bondarev <obondarev@mirantis.com> 1559042546 +0000

Bump fs.inotify.max_user_instances on compute nodes for scale

This problem appeared with one of latest dnsmasq versions.

Since each dnsmasq process consumes one inotify socket, the default
value of fs.inotify.max_user_instances which is 128 lets us scale to
only around a 116 neutron subnets (a few other sockets are used by other
processes on the system). Since, we need to provide better defaults,
this patch proposes to bump this value to 1024 by default, while giving
the user a way to cahnge it. Based on
https://unix.stackexchange.com/a/13757 each inotify watch takes 1KB of
memory and we have fs.inotify.max_user_watches set to 8192 by default.
This means that even in the worst case we won't be using more than 8MB
of memory. Bumping the fs.inotify.max_user_instances value to 4096 is
safe because there is fs.inotify.max_user_watches which caps the total
number of files that can be watched by all the inotify instances a user

Change-Id: I5794bd9c815c24302a707a1b88a5c25caa6ee953
Related-Prod: PROD-30216