广播式共享存储器──一种新的多计算机系统通讯结构

提出一种用于多机系统节．点机间通讯的新结构──广播式共享存储器．每个节点机都有一个双口ＳＲＡＭ，Ａ口供本节点机“只读”，Ｂ口均连到公共“广播写”总线，供争到总线使用权的节点机广播写数，实现数据通讯．这种多机系统既具有共享存储器便于并行编程的优点，又能显著降低访问共享存储器发生冲突的概率，具有很好的性能价格比。本文所提出的通讯方案已用于由８个ｉ８６０微处理器组成的多机系统中（峰值速度达６４０ＭＦＬＯＰＳ）实验的结果表明，这种方案可使节点机间的通讯速率得到大幅度提高。

Broadcast Shared Memory-a New Communication Structure for Multi-Computer System

In this paper, a new communication structure for multicomputer system, broadcast sharedmemory, is proposed. There are a dualport SRAM and a local DRAM in each node. All dualprotSRAMs construct a unified broadcast shared memory. The port B's of all SRAMs are connected tothe same broadcast bus. While writing, the node computer with highest priority via arbitration logiccan broadcast shared variables into all SRAMs. The port A of each SRAM is directly connected to anode computer, so each node can read shared variables simultaneously. There are still contentionsduring "Write", but they drop down greatly as only shared variables are stored in SRAMs. Themethod to solve the difficulty during parallel programming resulting from discontinuous memoryspace of SRAM and DRAM is also introduced.The new technique has been proved out in a prototype system, composed of 4 Transputcr T800s,with a communication rate of 26MB/s, as high as 13 times of that of transputer link.Users writeprogram for each node in traditiona] sequential Fortran or C, without the need of parallel languages.We are developing a new prototype system composed of 8 i860 with 640 MFLOPS peak speed.