Towards Energy Proportionality for Large-Scale Latency-Critical Workloads
Venue
Proceedings of the 41th Annual International Symposium on Computer Architecture, ACM (2014)
Publication Year
2014
Authors
David Lo, Liqun Cheng, Rama Govindaraju, Luiz André Barroso, Christos Kozyrakis
BibTeX
Abstract
Reducing the energy footprint of warehouse-scale computer (WSC) systems is key to
their affordability, yet difficult to achieve in practice. The lack of energy
proportionality of typical WSC hardware and the fact that important workloads (such
as search) require all servers to remain up regardless of traffic intensity renders
existing power management techniques ineffective at reducing WSC energy use. We
present PEGASUS, a feedback-based controller that significantly improves the energy
proportionality of WSC systems, as demonstrated by a real implementation in a
Google search cluster. PEGASUS uses request latency statistics to dynamically
adjust server power management limits in a fine-grain manner, running each server
just fast enough to meet global service-level latency objectives. In large cluster
experiments, PEGASUS reduces power consumption by up to 20%. We also estimate that
a distributed version of PEGASUS can nearly double these savings.
