Performance evaluation of a WDMA OIDSM multiprocessors

Optically interconnected distributed shared memory (OIDSM) systems offer significant performance advantages due to the fast interconnection network. The photonic network of the proposed approach is based on a wavelength-division multiplexed (WDMA) passive star-coupled configuration. Optical self-routing is achievable which partitions the traffic, relaxing the design constraints on the receiver subsystem since a node now only receives and processes a fraction of the network traffic. A major concern with the multi-access approach is that a media access control and a cache coherence protocol are required to provide access to a distributed arbitration of the WDMA photonic network. In particular, one class of media access protocol (TDMAC) requires a control channel to broadcast reservation requests, and the broadcast capability is also able to support coherence level control signals such as invalidations which enable a snooping based coherence protocol. This paper evaluates how OIDSM can ease the traffic in large-scale snooping-based shared memory multiprocessors.