Sizes of on-chip caches on current commercial microprocessors range from 16 Kbytes to 36 Kbytes. These microprocessors can be directly used in the design of a low cost single-bus shared memory multiprocessors without using any second-level cache. In this paper, we explore the viability of such a multi-microprocessor. Simulations results clearly establish that performance of such a system will be quite poor if on-chip caches are direct-mapped. On the other hand, when the on-chip caches are partially associative, the achieved level of performance is quite promising. In particular, two recently proposed innovative cache structures, the skewed-associative cache organization and the semi-unified cache organization are shown to work fine.
A virtual-physical on-chip cache for shared memory multiprocessors
