Execution time optimisation using delayed multidimensional retiming

Abstract

Multidimensional Retiming (MR) is a software pipelining approach that ensures increasing the instruction-level parallelism across all the nested loops. All the MR techniques aim at achieving a full parallelism in order to schedule applications with a minimal cycle period. However, the growth of code sizes in terms of parallelism level engenders the rise in cycle period numbers. Thus, fully parallel multidimensional applications frequently face limiting factors when implemented on real-time systems. This paper presents a novel technique, called delayed MR, which schedules nested loops with a minimal cycle period, without achieving full parallelism. It is formulated into two efficient steps whose first one sweeps the nested loops with the target of selecting and ordering paths, whereas the second one applies an optimal MR to the selected paths. Our technique is verified by implementing several nested loops in NVIDIA architectures. The experimental results show that our technique achieves average improvements on execution time of 32.8% compared to the incremental technique and 19.35% compared to the chained one.