Response-Time Distribution in a Real-Time Database with Optimistic Concurrency211 Control and General Execution Times

摘要

For a real-time shared-memory database with optimistic concurrency control, an211u001eapproximation for the distribution of the transaction response time and thus for 211u001ethe deadline miss probability is obtained. Transactions arrive at the database 211u001eaccording to a Poisson process. There is a limited number of CPUs that can handle 211u001etransactions in parallel. Transactions have soft deadlines, and the probability 211u001eof data conflicts is equal for all transactions. No restrictive assumptions are 211u001eneeded about the execution time of transactions: it can have any general 211u001eprobability distribution. The authors approximate the behavior of the system by a 211u001emulti-server queue with a special type of feedback. The analysis if this queueing 211u001esystem is based on an interpolation of the corresponding systems with constant 211u001eand exponential execution times. Numerical experiments, which compare the 211u001eapproximative analysis with a simulation of the database, show that the 211u001eapproximation of the response-time distribution is quite accurate and thus very 211u001euseful for real-time database design.