Directoryless shared memory coherence using execution migration
Author(s)Lis, Mieszko; Shim, Keun Sup; Cho, Myong Hyon; Khan, Omer; Devadas, Srinivas
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We introduce the concept of deadlock-free migration-based coherent shared memory to the NUCA family of architectures. Migration-based architectures move threads among cores to guarantee sequential semantics in large multicores. Using a execution migration (EM) architecture, we achieve performance comparable to directory-based architectures without using directories: avoiding automatic data replication significantly reduces cache miss rates, while a fast network-level thread migration scheme takes advantage of shared data locality to reduce remote cache accesses that limit traditional NUCA performance. EM area and energy consumption are very competitive, and, on the average, it outperforms a directory-based MOESI baseline by 1.3 x and a traditional S-NUCA design by 1.2 x. We argue that with EM scaling performance has much lower cost and design complexity than in directory based coherence and traditional NUCA architectures: by merely scaling network bandwidth from 256 to 512 bit flits, the performance of our architecture improves by an additional 13%, while the baselines show negligible improvement.
DepartmentMassachusetts Institute of Technology. Computer Science and Artificial Intelligence Laboratory; Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Parallel and Distributed Computing and Systems
Lis, Mieszko et al. “Directoryless Shared Memory Coherence Using Execution Migration.” Parallel and Distributed Computing and Systems, December 2011.
Author's final manuscript