Evolutionary-based conflict-free scheduling of collective communications on spidergon NoCs.

The Spidergon interconnection network has become popular recently in multiprocessor systems on chips. To the best of our knowledge, algorithms for collective communications (CC) have not been discussed in the literature as yet, contrary to pair-wise routing algorithms. The paper investigates complexity of CCs in terms of lower bounds on the number of communication steps at conflict-free scheduling. The considered networks on chip make use of wormhole switching, full duplex links and all-port non-combining nodes. A search for conflict-free scheduling of CCs has been done by means of evolutionary algorithms and the resulting numbers of communication steps have been summarized and compared to lower bounds. Time performance of CCs can be evaluated from the obtained number of steps, the given start-up time and link bandwidth. Performance prediction of applications with CCs among computing nodes of the Spidergon network is thus possible.