Issue No.07 - July (2008 vol.57)
Patrick Ndai , Purdue University, West Lafayette
Swarup Bhunia , Case Western Reserve University, Cleveland
Amit Agarwal , Intel Corporation, Hillsboro
Kaushik Roy , Purdue University, West Lafayette
DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/TC.2008.40
Within-die parameter variations can cause wide delay distribution among similar functional units in superscalar processors. Conventionally, the frequency of operation is reduced to accommodate the slowest unit, which in turn degrades throughput. We present a low-overhead design technique that sets the operating frequency in a superscalar processor based on the faster units, and allows more cycles for the slower units. We propose an associated priority scheduling strategy to schedule instructions in the functional units to maximize throughput. Simulation results on a set of benchmarks show that by assigning a higher scheduling priority to faster units, we can achieve 18% improvement in performance on average with negligible design overhead.
Superscalar Processors, Scheduling, Variable-cycle functional unit, process variation, speed binning.
Patrick Ndai, Swarup Bhunia, Amit Agarwal, Kaushik Roy, "Within-Die Variation-Aware Scheduling in Superscalar Processors for Improved Throughput", IEEE Transactions on Computers, vol.57, no. 7, pp. 940-951, July 2008, doi:10.1109/TC.2008.40