Exploring the diversity of multimedia systems

Abstract

We evaluate the validity of the fundamental assumption behind application-specific programmable processors: that applications differ from each other in key parameters which are exploitable, such as the available instruction-level parallelism (ILP), demand on various hardware resources, and the desired mix of function units. Following the tradition of the CAD community, we develop an accurate chip area estimate and a set of aggressive hardware optimization algorithms. We follow the tradition of the architecture community by using comprehensive real-life benchmarks and production quality tools. This combination enables us to build a unique framework for system-level synthesis and to gain valuable insights about design and use of application-specific programmable processors for modern applications. We explore the application-specific programmable processor (ASSP) design space to understand the relationship between performance and area. The architecture model we used is the Hewlett Packard PA-RISC with single level caches. The system, including all memory and bus latencies, is simulated and no other specialized ALU or memory structures are being used. The experimental results reveal a number of important characteristics of the ASSP design space. For example, we found that in most cases a single programmable architecture performs similarly to a set of architectures that are tuned to individual application. A notable exception is highly cost sensitive designs, which we observe need a small number of specialized architectures that require smaller areas. Also, it is clear that there is enough parallelism in the typical media and communication applications to justify use of high number of function units. We found that the framework introduced in this paper can be very valuable in making early design decisions such as area and architectural configuration tradeoff, cache and issue width tradeoff under area constraint, and the number of branch units and issue width.