Request queueing for magnetic bubble memories

The improvements in request throughput that result from the use of the shortest seek time first (SSTF) request, scheduling algorithm for major/minor loop organized magnetic bubble memories are considered. For the satisfaction of read requests the bubble memory can be considered as equivalent to a file drum with fixed block size. Bubble memories are considered with 64 kbits per chip running at a 5.6 μs stepping rate and serving 750 to 830 read requests pet second (as opposed to ≤ 419 requests per second without queueing) with both uniform and Poisson arrival rates. A priority interrupt algorithm is implemented that assures that all requests are served in ≤ 60ms, while average service times are 10 to 20 ms. Results of simulation runs, corresponding to the various cases of interest, are presented. It is concluded that request queueing with the appropriate scheduling algorithm is a practical way of improving bubble memory performance.