A design space evaluation of grid processor architectures

In this paper we survey the design space of a new class of architectures called Grid Processor Architectures (GPAs). These architectures are designed to scale with technology, allowing faster clock rates than conventional architectures while providing superior instruction-level parallelism on traditional workloads and high performance across a range of application classes. A GPA consists of an array of ALUs, each with limited control, connected by a thin operand network. Programs are executed by mapping blocks of statically scheduled instructions to the ALU array and executing them dynamically in dataflow order. This organization enables the critical paths of instruction blocks to be executed on chains of ALUs without transmitting temporary values back to the register file, avoiding most of the large, unscalable structures that limit the scability of conventional architectures. Finally, we present simulation results of a preliminary design, the GPA-1. With a half-cycle routing delay, we obtain performance roughly equal to an ideal 8-way, 512-entry window superscalar core. With no inter-ALU delay, perfect memory, and perfect branch prediction, the IPC of the GPA-1 is more than twice that of the ideal superscalar core, achieving an average of 111PC across nine SPEC CPU2000 and Mediabench benchmarks.