MESA: reducing cache conflicts by integrating static and run-time methods

Abstract

The paper proposes MESA (Multicoloring with Embedded Skewed Associativity), a novel cache indexing scheme that integrates dynamic page coloring with static skewed associativity to reduce conflicts in L2/L3 caches with a small degree of associativity. MESA associates multiple cache pages (colors) with each virtual memory page and uses two-level skewed associativity, first to map a page to a different color in each bank of the cache, and then to disperse the lines of a page across the banks and within the colors of the page. MESA is a multi-grained cache indexing scheme that combines the best of two worlds, page coloring and skewed associativity. We also propose a novel cache management scheme based on page remapping, which uses cache miss imbalance between colors in each bank as the metric to track conflicts and trigger remapping. We evaluate MESA using 24 benchmarks from multiple application domains and with various degrees of sensitivity to conflict misses, on both an in-order issue processor (using complete system simulation) and an out-of-order issue processor (using SimpleScalar). MESA outperforms skewed associativity, prime modulo hashing, and dynamic page coloring schemes proposed earlier. Compared to a 4-way associative cache, MESA can provide as much as 76% improvement in IPC.