14
V. Liberatore
Pervasive Computing
QoS Assurances
*So, what do we want from QoS?
*Worst-case
nReasoning
*Reason about system timing
*Priorities make it easy
nIs it cross-traffic?
nIs it failures (e.g., network partition)?
nFailures as first class citizens
*Average-case
nNon-sense
nExacerbated by TCP
*Tail
nE.g., 99-percentile
nMust be paired with middleware, fault-tolerance