Appeared in: IEEE Workshop on Parallel and Distributed RT Systems, pp 118-121, Hawaii, April, 1996.
It is assumed that transactions arrive according to a Poisson process, execution times of transactions are independent and exponentially distributed, and all transactions use the same number of data items. The system is then represented as a Markov model. A steady state is derived from this model. By examining the path through the system of a single transaction, a recursive relation that describes all moments of a transaction's response time is derived.
The response time distribution is approximated by fitting a distribution to the first two moments. Simulation shows that this approximation gives excellent results.