IODET: A HoL-blocking-aware Deterministic Routing Algorithm for Direct Topologies

In large parallel computers routing is a key design point to obtain the maximum possible performance out of the interconnection network. Routing can be classified into two categories depending on the number of routing options that a packet can use to go from its source to its destination. If the packet can only use a single predetermined path then the routing is deterministic, whereas if several paths are possible it is adaptive. It is a well-known fact that adaptive routing usually outperforms deterministic routing; but in this paper we take the challenge of developing a HOL-blocking-aware deterministic routing algorithm that can obtain a similar or even better performance than adaptive routing, while decreasing its implementation complexity and providing some inherent advantages to deterministic routing such as in-order delivery of packets. In this large computers regular direct topologies are widely-used, so in this paper we focus on meshes and tori.