Modeling and Characterizing Power Variability in Multicore Architectures

Parameter variation due to manufacturing error is an unavoidable consequence of technology scaling in future generations. The impact of random variation in physical factors such as gate length and interconnect spacing have a profound impact on not only performance of chips, but also their power behavior. While circuit-level techniques such as adaptive body-biasing can help to mitigate mal-fabricated chips, they cannot completely alleviate severe within die variations forecasted for near future designs. Despite the large impact that power variability have on future designs, there is a lack of published work that examines architectural implications of this phenomenon. In this work, we develop architecture level models that model power variability due to manufacturing error and examine its influence on multicore designs. We introduce VariPower, a tool for modeling power variability based on an microarchitectural description and floorplan of a chip. In particular, our models are based on layout level SPICE simulations and project power variability for different microarchitectural blocks using statistical analysis. Using VariPower: (1) we characterize power variability for multicore processors, (2) explore application sensitivity to power variability, and (3) examine clustering techniques that can appropriately classify groups of processors and chips that have similar variability characteristics