ANU Computer Science Technical Reports

TR-CS-12-01


Ting Cao, Tiejun Gao, Stephen M Blackburn, and Kathryn S McKinley.
System Design for Heterogeneity: The Virtual Machine Services Test Case.
January 2012.

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Abstract: Power and energy constraints are forcing architects to propose heterogeneous parallel systems. Unfortunately, tuning or customizing parallel hardware for a particular application compromises application portability. This paper focuses on the class of heterogeneous systems that combine general-purpose big and small cores for portability. This paper identifies key software characteristics and a framework for exploiting them to improve performance, power, and energy on big/small multicores: (1) parallelism, (2) asynchrony, (3) criticality, and (4) hardware sensitivity. We choose Virtual Machine (VM) services executing managed languages as our workload. They are pervasive (e.g., JavaScript, PHP, Java, and C#), dominate power and energy constrained platforms, such as the phone and tablet, do not compromise application portability, and use a lot of energy. VM services interpret, compile, profile, schedule, and manage memory while executing applications. Fortunately, VM services are often parallel, asynchronous, not on the application's critical path, and are power and energy efficient on small cores. This paper demonstrates (a) that VM services consume a lot of power and energy, almost 40% in modern systems; (b) how to exploit unique combinations of the four characteristics in VM services to lower power, improve performance, and improve performance per energy (PPE); and (c) that using big cores for application threads together with tuned small low-power cores for VM services can substantially lower power and improve performance per energy (PPE). These results suggest that other system services, additional architecture tuning or customization, and software/hardware co-design are fruitful future directions for improving PPE and meeting power constraints.
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Last modified: Tue Mar 20 17:43:04 EST 2012