Twiste d Torus Topologies for Enhanced Interconnection Networks
Cámara, J.M. and Moretó, M. and Vallejo, E. and Beivide, R. and Miguel- Alonso, J. and Martinez, C. and Navaridas, J.
Abstract
Many current parallel computers are built around a torus interconnect ion network. Machines from Cray, HP, and IBM, among others, make use of this to pology. In terms of topological advantages, square (2D) or cubic (3D) tori woul d be the topologies of choice. However, for different practical reasons, 2D and 3D tori with different number of nodes per dimension have been used. These mix ed-radix topologies are not edge symmetric, which translates into poor performa nce due to an unbalanced use of network resources. In this work, we analyze twi sted 2D and 3D mixed-radix tori that remove the network bottlenecks present in nontwisted ones. Such topologies recover edge symmetry, and consequently, balan ce the utilization of their links. The distance-related properties of twisted t ori together with a full characterization of their bisection bandwidth are desc ribed in this paper. A simulation-based performance evaluation has been carried out to assess the network performance under synthetic and trace-driven workloa ds. The obtained results show noticeable and consistent performance gains (up t o an increase of 74 percent in accepted load). In addition, we propose scalable and practicable packet routing mechanisms and wiring layouts for these interco nnection systems. The complexity of the architectural proposals is similar to t he one exhibited by routing and folding mechanisms in standard tori.