Scalable Directory Protocols for 1000s of Cores Dominic DiTomaso EE 6633.
Scalable Directory Protocols for 1000s of Cores
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Scalable Directory Protocols for 1000s of Cores Dominic DiTomaso EE 6633
description
Scalable Directory Protocols for 1000s of Cores. Dominic DiTomaso EE 6633. Outline. Introduction Background ATAC SPATL Cuckoo Directory SCD Conclusions. Directory Protocols. Snoopy (broadcast) -> Directory (multicast) Large Directory Overhead Overhead = P*M P - # of processors - PowerPoint PPT Presentation
Transcript of Scalable Directory Protocols for 1000s of Cores
Scalable Directory Protocols for 1000s of CoresDominic DiTomasoEE 6633
Outline
• Introduction•Background
• ATAC• SPATL• Cuckoo Directory
•SCD•Conclusions
Directory Protocols• Snoopy (broadcast) -> Directory (multicast)
• Large Directory Overhead• Overhead = P*M• P - # of processors• M - # of memory blocks
• 64 nodes: 12.7% overhead• 256 nodes: 50% overhead• 1024 nodes: 200% overhead
P
M
Directory Protocols• Requirements
• Small area, energy, and latency overheads• Accurate sharer information• Limited directory-induced invalidations
• Duplicate Tags• Area-efficient• High associativity -> high power
• Sparse Directory• Power-efficient• Large capacity -> large area
• Coarse-grain vectors, Hierarchical, etc.
ATAC• Optical Broadcast Network
SPATL• Tagless• Bloom Filters
Cuckoo Directory• N-ary Cuckoo Hash Table
SCD• Variable directory tags
SCD (cont.)
SCD (cont.)
Conclusions• Large directory overhead at 1000s of cores• Solutions
• Optics – ATAC• Tagless – SPATL• Hash Tables – Cuckoo• Variable Tags – SCD
References• [1] George Kurian, Jason E. Miller, James Psota, Jonathan Eastep, Jifeng Liu,
Jurgen Michel, Lionel C. Kimerling, and Anant Agarwal, “ATAC: a 1000-core cache-coherent processor with on-chip optical network,” In Proceedings of the 19th international conference on Parallel architectures and compilation techniques (PACT '10), 2010.
• [2] Daniel Sanchez and Christos Kozyrakis, “SCD: A scalable coherence directory with flexible sharer set encoding,” In Proceedings of the 2012 IEEE 18th International Symposium on High-Performance Computer Architecture (HPCA '12), 2012.
• [3] H. Zhao, A. Shriraman, S. Dwarkadas, and V. Srinivasan, “SPATL: Honey, I Shrunk the Coherence Directory,” In Proceedings of the 20th international conference on Parallel architectures and compilation techniques (PACT ’11), 2011.
• [4] M. Ferdman, P. Lotfi-Kamran, K. Balet, B. Falsafi, "Cuckoo directory: A scalable directory for many-core systems," 2011 IEEE 17th International Symposium on High Performance Computer Architecture (HPCA), pp.169-180, Feb. 2011.
