Combined Application of Data Transfer and Storage Optimizing Transformations and Subword Parallelism Exploitation for Power Consumption and Execution Time Reduction in VLIW Multimedia Processors

摘要

In this paper the important issues in mapping data dominated multimedia applications on Very Long Instruction Word (VLIW) multimedia processors are addressed. The main design quality factors of applications realized on the target architecture platform are presented and their interactions are explored. Power consumption is the major cost factor while performance is the overriding constraint in realizations of multimedia applications on the target architecture platform. A methodology for the reduction of the data transfer and storage related power consumption, which forms an important part of the total power budget of the system, and the execution time of applications realized on VLIW multimedia processors, has been developed. The methodology is based on the application of a number of transformations, mainly oriented towards data transfer and storage optimization, to a high level description of the target application. The main focus of this paper is on the interaction of the proposed code transformations with the exploitation of subword parallelism (for example through the application of special performance improving arithmetic subword instructions present in modern VLIW multimedia processors). Experimental results from real-life data-dominated multimedia applications clearly demonstrate that the application of the proposed transformations is orthogonal to the exploitation of subword parallelism. A second conclusion is that the positive impact of the proposed code transformations on performance is typically even larger than the effect of the subword parallelism exploitation for the complete application. The effect of the subword parallelism exploitation is even enhanced after the application of the proposed code transformations.