Qpr.Js: A Runtime Framework For Qos-Aware Power Optimization For Parallel Javascript Programs

JavaScript has become a general-purpose programming environment that enables complex, media-rich web applications. An increasing number of JavaScript programs are parallelized to run efficiently on today's multicore CPUs, which are capable of dynamic core scaling (DCS) and voltage/frequency scaling (DVFS). However, significant power savings are still left on the table since an operating point (in terms of the number of active cores and CPU voltage/frequency) is selected by monitoring CPU utilization or OS events, without considering the user's performance goal. To address this, we propose QPR.js, a QoS-aware power-optimizing runtime system for JavaScript. Using the QPR.js API, the application developer can specify a QoS goal and provide a fitness function to quantify the current level of QoS. During execution the QPR.js runtime system uses this information to autonomously find an optimal operating point minimizing power consumption while satisfying the QoS goal. Our evaluation with five parallel JavaScript programs demonstrates an average of 35.2% power savings over the Linux Ondemand governor without degrading user experience.