Livelock and system responsivity

A system is UNRESPONSIVE when it rarely or never processes userland tasks.
in principle can still do some useful work, e.g. forward packets.
userland apps have no cycles to run.

A system is in LIVELOCK when it does not manage to complete any useful work.
common in servers or router boxes: packets are received and queued for further service, which never has a chance to happen.

Both phenomena are undesirable, because they can render a system unable to perform its duties as the load increases.