Cloned from launchpad blueprint https://blueprints.launchpad.net/nova/+spec/libvirt-image-cache-enhancement.
According to https://bugs.launchpad.net/nova/+bug/1253991, I think it would be better to use a bp instead of a bug fix
some enhancement that I want to address in steps
1) to do image cache management for swap disk, to remove the cache if it's not used anymore for long time
2) to do image cache management for eph disk, like swap disk
3) some log enhancement for periodic task lead to error logs (like https://bugs.launchpad.net/nova/+bug/1261442 does)
Specification URL (additional information):