These are a few tweaks I applied to my own memory-constrained cloud
instances that seemed to help. I have lower performance requirements
so this may make things worse and not better, but it's worth seeing
what the impact is. I'll admit to not knowing the full impact of these
as they're mostly collected from various tutorials on lowering memory
usage.
Enable this for now on devstack-multinode
Change-Id: I7b223391d3de01e3e81b02076debd01d9d2f097c