Improving parallel system performance by changing the arrangement of the network links

International Conference on Supercomputing


The Midimew network is an excellent contender for implementing the communication subsystem of a high performance computer. This network is an optimal 2D topology in the sense there are no other symmetric direct networks of degree 4 with a lower average distance or diameter. In fact, it reduces the diameter of the well known torus network by approximately √2 . Although the topology was proposed and analyzed a decade ago, the lack of simple deadlock avoidance mechanisms prevented its utilization up to date. This study solved this drawback by applying the Bubble switching mechanism, a low cost deadlock-avoidance strategy developed by the authors. Moreover, by using routing tables we can configure our Virtual Cut-Through adaptive router to implement either a torus or a Midimew network. Thus, we can exploit the topological advantages of Midimew networks by simply changing the disposition of the wrap-around connections of its torus counterpart, without increasing the network implementation cost. To prove this assertion, we have carried out a thorough evaluation, from the hardware cost of the router to the parallel system performance under real loads.