The performance enhancement of descriptor-based virtual memory systems through the use of associative registers

摘要

Contemporary paged virtual memory systems often use associative registers to reduce access time to frequently-referenced pages. Here we examine the analogous use of associative registers in descriptorbased, symbolically-segmented virtual memory systems, where each segment contains an entire data structure as defined in a high-level language. Symbolic trace data from production Algol 60 programs were used to determine performance improvement as a function of the number of associative registers in the system. Our results indicate that, even for reasonably large programs, a hit ratio of 0.9 is achieved with only 4 associative registers. Increasing the number of associative registers to 8 gives a hit ratio of 0.98, which with current technology gives a performance improvement of at least 80% in addressing speed over a similar system without associative registers.