Unified vs. split TLBs and caches in shared-memory MP systems

Data references in shared-memory multiprocessors (SMMPs) are targeted to private and shared data. Thus, conflicts between private and shared data occur in unified translation-lookaside buffer (TLBs) and caches. Separate private and shared data TLBs and caches eliminate such conflicts and might decrease miss ratios. But these split TLBs and caches would be smaller than their unified counterparts and might increase miss ratios. We use trace-driven simulations to compare the performance of unified vs. split data TLBs and caches. Our results show (1) a small number of unified TLB/cache conflicts for two workloads and a substantial number for another; and (2) split TLB/cache miss ratio reductions due to conflict removal smaller than miss ratio increases due to reduced size. Although split data TLBs and caches do not offer performance gains in SMMPs for such workloads, it is not clear whether or not they would for different workloads