Path-Dividing Based Scheduling Algorithm for Reducing Energy Consumption of Clustered VLIW Architectures

This paper presents an instruction scheduling algorithm for clustered very long instruction words (VLIW) architectures. It exploits a path-dividing-based technique to decide a more appropriate processing order of instructions, and utilizes a more global view to generate the scheduling result by simultaneously considering the influence of both data dependence relations between instructions and distribution of instructions among clusters. The algorithm is composed of two stages. The first stage virtually schedules all the instructions based on the path-dividing technique. The cluster virtually assigned in the first stage is delivered to the second stage. While the cycle virtually scheduled in the first stage is only used in this stage for the purpose of taking into account the implications between cluster assignment and cycle scheduling. The second stage performs actual scheduling according to the cluster assignment decisions made in the first stage and generates final scheduling results. The proposed algorithm is implemented and evaluated with benchmarks extracted from UTDSP and MediaBench. Results show that the improvement is impressive. Besides producing a large reduction in energy consumption, the algorithm can also make a remarkably performance speed-up. The average energy consumption ranges from 28.1% (4-Clusters) to 37.3% (8-Clusters). And the average speed-up ranges from 29.9% (4-Clusters) to 39.1% (8-Clusters).