An Optical Bus Computer Cluster with a deferred cache coherence protocol

Abstract

I n this paper, we first propose a class of workstation cluster which utilizes optical wavelength-division multaplextng (WDM) technology to connect nodes (workstations) of the cluster. The Optical Bus Computer Cluster OBCC) falls an the class of cache coherent non-uni / o r m memory access (CC-NUMA) multiprocessors. The basic topology of the cluster is starshaped with a n optical star-coupler in the center to enable one-hop simultaneous broadcasting of information packets from one node to all other cluster nodes. WDM technology not only multiplies by N times the network bandwidth using a single optical fiber, where N is the degree of wavelength multiplexing, but also provides independent communication paths between pairs of cluster nodes by properly assigning wavelengths to inter-node communication. Then we identijy the cache subsystem requirements for the OBCC and propose a deferred cache coherence protocol suitable for the OBCC. The basic coherence maintenance scheme is to lazy-evaluate the cache coherence transactions among cluster nodes, utilizing the weak consistency memory model. B y deferring the transactions, it is possible to combine multiple transaction issues into one transaction by accumulating modified status bits in the enhanced cache status fields. Since not only the remote memory access but also coherence transaction are costly operations in CC-NUMA systems, the deferred invocation of coherence transactions is particularly useful in CC-NUMA systems such as OBCC. W e then give a performance evaluation by simulation that the coherence protocol effectively reduces coherence transactions, particularly in situations where false sharing of longer cache lines becomes noticeable.

Optoelectronic interconnection technology in the holms system

“…In addition, different theoretical architecture concepts have been developed [13], [15], [26]. In this context, a considerable amount of attention has also been given to the issue of optical interconnections in shared memory systems [7], [13], [18], [21], [30], [45].…”

Real3 communication and aromatic group computing

“…Our "optical bus cluster" technology can directly interconnect computers with an optical bus and handle closely-coupled computer resources as if they were a single unit [3]. The computer integration technologies such as parallel architecture and distributed OS form the basis c~f realtime multimedia communication.…”