A Non-blocking Directory Protocol for Large-Scale Multiprocessors

Date of Submission: 
April 8, 1999
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This paper presents a non-blocking directory-based cache coherence protocol to improve the performance of large-scale distributed shared-memory multiprocessors. In the proposed non-blocking directory protocol, all subsequent request can proceed without being blocked at the directory. The critical path of a data access and the amount of network transactions needed to complete a memory request (including the transactions needed to maintain coherence) are also reduced. To support the non-blocking directory protocol, the history of data accesses is maintained with a small history table at the directory. Using detailed simulations,we evaluate the performance of the protocol compared with other blocking directory protocols.