Improved Modeling and Data Migration for Dynamic Non-Uniform Cache Accesses

Growing wire delay and clock rates limit the amount of cache accessible within a single cycle. Non-uniform cache access (NUCA) has been proposed as a solution to this problem in Kim et al, 2002 [1], and performance has been analyzed for various cache organizations and technology assumptions. Innovations included cache organizations which dynamically migrated data between blocks within the cache (D-NUCA) resulting in 11 % improvement in SPEC2000 benchmarks over a static (S-NUCA) approach. Our work duplicates, verifies and extends the work of [1] in the following ways: 1) a commercial microprocessor, the Compaq Alpha 21364 is used for a realistic floorplan (an admitted limitation by the authors of [1]), cache sizes and wire delay estimates, 2) process technology nodes 130nm, 90nm and 65nm are used to explore the scaling of the proposed approach, and 3) new topologies and policies are developed for migrating data within the cache. Our results generally corroborate those of [1] and show that the realistic floorplan results in a 16 % increased performance. Furthermore, our improved topology and policies for movement of data within the cache result in still improved performance of 43%. It should be noted that there is wide variation in the improvement of the different SPEC2000 benchmarks, thus pointing to future compilerlevel approaches to D-NUCA exploitation