  JSC NICEVT has developed the Angara high-speed interconnect with 4D torus
topology. The Angara interconnect router implements deterministic routing based
on the bubble flow control, a direction order routing (DOR) and direction bits
rules. The router chip also supports non standard First Step / Last Step for
bypassing failed nodes and links, these steps can violate the DOR rule. In the
previous work we have proposed an algorithm for generation and analysis of
routing tables that guarantees no deadlocks in the Angara interconnect. It is
based on a breadth-first search algorithm in a graph and it practically does
not take into consideration communication channel load. Also we have never
evaluated the influence of routing table generation algorithm on the
performance of a real-world Angara based cluster. In this paper we present a
routing graph notation that provides a possibility to build routes in the torus
topology of the Angara interconnect. We propose a deadlock-free routing
algorithm based on a fast single-source shortest path algorithm for the
deterministic Angara routing with a single virtual channel. We evaluated the
considered routing algorithms on a 32-node Desmos cluster system and
benchmarked the proposed algorithm performance improvement of 11.1% for the
Alltoall communication pattern and of more than 5% for the FT and IS
application kernels.
