  SMART NoC, which transmits unconflicted flits to distant processing elements
(PEs) in one cycle through the express bypass, is a high-performance NoC design
proposed recently. However, if contention occurs, flits with low priority would
not only be buffered but also could not fully utilize bypass. Although there
exist several routing algorithms that decrease contentions by rounding busy
routers and links, they cannot be directly applicable to SMART since it lacks
the support for arbitrary-turn (i.e., the number and direction of turns are
free of constraints) routing. Thus, in this article, to minimize contentions
and further utilize bypass, we propose an improved SMART NoC, called ArSMART,
in which arbitrary-turn transmission is enabled. Specifically, ArSMART divides
the whole NoC into multiple clusters where the route computation is conducted
by the cluster controller and the data forwarding is performed by the
bufferless reconfigurable router. Since the long-range transmission in SMART
NoC needs to bypass the intermediate arbitration, to enable this feature, we
directly configure the input and output ports connection rather than apply
hop-by-hop table-based arbitration. To further explore the higher communication
capabilities, effective adaptive routing algorithms that are compatible with
ArSMART are proposed. The route computation overhead, one of the main concerns
for adaptive routing algorithms, is hidden by our carefully designed control
mechanism. Compared with the state-of-the-art SMART NoC, the experimental
results demonstrate an average reduction of 40.7% in application schedule
length and 29.7% in energy consumption.
