In this paper we investigate architectures that combine message-passing and
shared-memory technologies, called hereinafter hybrid architectures, We in
troduced hybrid architectures in which large buses of the shared-memory are
split into a number of small high-performance shared-memory blocks, which
are connected via message-passing architecture, such as hypercube, grid or
ring. This way we avoid the possible degradation of the achieved performanc
e due to the fact that the bus performance does not scale well when the num
ber of processors it connects increases.
We study the saturation situations of several hybrid network architectures,
where adding processors does not reduce the overall execution time. We sho
w that the use of hybrid network architectures leads to significant improve
ment of the systems price/performance ratio, by significantly improving the
performance with almost no system cost increment, Therefore, the usage of
hybrid architectures demonstrates how minimal 'cost' spending could signifi
cantly increase the system performance. In addition, we show that different
types of applications have different best hybrid architectures, Copyright
(C) 2000 John Wiley & Sons, Ltd.