Measuring limits of parallelism and characterizing its vulnerability to resource constraints

Addresses a two-fold question: whether there is enough parallelism in numeric and non-numeric workloads, such as the SPEC92 benchmark suite, under ideal conditions, disregarding any resource constraints and more importantly, whether a high ideal parallelism can be further characterized to assess its extractability with finite resources. The authors have designed and implemented an analysis tool that accepts as input a dynamic execution trace from an IBM RS/6000 environment, and outputs a parallelized instruction trace (schedule) that could be executed on an abstract machine with unlimited functional units and various constraints on the rest of its resources, namely, registers, stack and memory. They also analyze two different instruction scheduling policies: greedy and lazy. The paper further offers a characterization of ideal parallelism (obtainable on a machine with infinite resources) using a measure called slack to assess its sustainability with finite resources