Two-Level Cache Performance for Multiprocessors

For shared bus multiprocessors operated in multiprogramming mode, the addition of second-level caches tends to significantly increase system performance. Trace-driven simulation was employed to obtain performance measurements over a range of system parameters, with the cache sizes at both levels being the parameters of most interest. For both light and heavy system loading, the addition of second-level caches was found to boost system performance. For heavily loaded multiprocessor cases, the workload-averaged percentage increases in performance ranged from 187% with 32k byte first-level caches to 507% with 4k byte first-level caches when 128k byte second- level caches were added. The main memory configuration and number of processors largely dictates the performance of a shared bus multiprocessor running in multiprogramming mode. The addition of larger second-level caches to the system results in increased system performance over a range of system configurations and workloads.