HaPPy: Hyperthread-aware Power Profiling Dynamically.

Quantifying the power consumption of individual applications co-running on a single server is a critical component for software-based power capping, scheduling, and provisioning techniques in modern datacenters. However, with the proliferation of hyperthreading in the last few generations of server-grade processor designs, the challenge of accurately and dynamically performing this power attribution to individual threads has been significantly exacerbated. Due to the sharing of core-level resources such as functional units, prior techniques are not suitable to attribute the power consumption between hyperthreads sharing a physical core. In this paper, we present a runtime mechanism that quantifies and attributes power consumption to individual jobs at fine granularity. Specifically, we introduce a hyperthread-aware power model that differentiates between the states when both hardware threads of a core are in use, and when only one thread is in use. By capturing these two different states, we are able to accurately attribute power to each logical CPU in modern servers. We conducted experiments with several Google production workloads on an Intel Sandy Bridge server. Compared to prior hyperthread-oblivious model, HaPPy is substantially more accurate, reducing the prediction error from 20.5% to 7.5% on average and from 31.5% to 9.4% in the worst case.