Abstract-A real-time stream is said to have (m, k)-firm deadlines if at least m out of any k consecutive customers from the stream must meet their respective deadlines. Such a stream is said to have encountered a dynamic failure if fewer than m out of any k consecutive customers meet their deadlines. Hamdaoui and Ramanathan recently proposed a scheduling policy called Distance Based Priority (DBP) in which customers are serviced with a higher priority if their streams are closer to a dynamic failure. In terms of reducing the probability of dynamic failure, Hamdaoui and Ramanathan also showed, using simulation, that the DBP policy is better than a policy in which all customers are serviced at the same priority level. In this paper, an analytic model is developed for computing the probability of dynamic failure of a real-time stream for the DBP and the single priority schemes. This model is useful for providing statistical quality of service guarantees to real-time streams. The probability of dynamic failure computed using this model is compared to the results from a discrete-event simulator. The comparison shows that the model is accurate for low and moderate loads.
REF presented an analytical model for computing the probability of dynamic failures on DBP.
Evaluating Dynamic Failure Probability for Streams with (m, k)-Firm Deadlines
IEEE Transactions on Computers
Computer Science