A power capping controller for multicore processors

Abstract

Abstract-This paper presents an online controller for tracking power-budgets in multicore processors using dynamic voltage-frequency scaling. The proposed control law comprises an integral controller whose gain is adjusted online based on the derivative of the power-frequency relationship. The control law is designed to achieve rapid settling time, and its tracking property is formally proven. Importantly, the controller design does not require off-line analysis of application workloads making it feasible for emerging heterogeneous and asymmetric multicore processors. Simulation results are presented for controlling power dissipation in multiple cores of an asymmetric multicore processor. Each core is i) equipped with the controller, ii) assigned a power budget, and iii) operates independently in tracking to its power budget. We use a cycle-level multicore simulator driven by traces from SPEC2006 benchmarks demonstrating that the proposed algorithm achieves a faster settling time than examples of a static setting of the controller gain.

Performance regulation and tracking via lookahead simulation: Preliminary results and validation

“…The resulting graph of the position y(t) is depicted by the dashed curve in Figure 3, and for the sake of reference we plotted r(t) by the dot-dashed curve. 2 We notice stability of the closed-loop system but no tracking; larger simulation horizons do not change this conclusion. It is not surprising in light of the discussion in Section II, since T is too large for g(u) to yield an adequate approximation for y(t + T ).…”

“…This issue can be addressed by ad-hoc methods like gradual increases of the gain α, which are beyond the scope of this paper but will be considered in the near future. 2 Actually the dot-dashed curve looks like a solid curve after the first halfcycle of the sinusoid since it is merged there with another graph (described below). The dot-dashed part of the sinusoid is visible during its first halfcycle.…”

“…However, purely integrative actions have been used, for example for the regulation of computer processors; Ref. [2] proposed a standalone integral controller endowed with a variable gain in order to enhance the stability margins of the closed-loop system. 1 This idea of a variable gain integrator can be generalized.…”

Temperature regulation in multicore processors using adjustable-gain integral controllers

“…The basic idea is to have the on-line computations of the integrator's gain be as simple and efficient as possible even at the expense of precision. This is made possible by a great degree of robustness of the tracking performance of the controller with respect to variations from the designed integrator's gain, which was observed from extensive simulations (see [20] for analysis and discussion). We verify the efficacy of our technique by simulations on a full system, cycle level simulator executing industry standard benchmark programs, and demonstrate rapid convergence despite the modeling errors and changing program loads.…”

“…We first applied the proposed approach in [20] for controlling the dynamic core power via DVFS. The problem considered here is more challenging for the following two reasons.…”