Admission Control Prototype for Real-Time Databases

We suggest and measure an admission control prototype for RTDBS, in which a transaction is presented to the system as a pair of procedures: a primary task, and a recovery block. The performance necessities of the main task are not known a priori, whereas those of the recovery block are known a priori. Upon the submission of a transaction, an Admission Control Mechanism is applied to determine whether to admit or reject that transaction. Once admitted, a transaction is assured to finish executing before its deadline. A transaction is considered to have finished executing if exactly one of two things occurs: Either its primary task is completed (successful commitment), or its recovery block is finished (safe termination). Committed transactions bring a profit to the system, whereas a terminated transaction brings no profit. The objective of the admission control and scheduling communications protocol (e.g., concurrency control, I /O scheduling, memory management) employed in the system is to maximize system profit. We depict a number of admission control strategies and contrast (through simulations) their relative performance.