Architecture of Computing Systems (Lecture Notes in Computer ...

A Hierarchical Distributed Control for
Power and Performances Optimization of
Embedded Systems
Patrick Bellasi 1 , William Fornaciari 1 ,andDavidSiorpaes 2
1 Politecnico di Milano, P.zza Leonardo da Vinci, 32. 20133 - Milano, Italy
bellasi@elet.polimi.it, fornacia@elet.polimi.it
2 STMicroelectronics, Via C. Olivetti, 2. 20041 - Agrate Brianza, Italy
david.siorpaes@st.com
Abstract. Power and resource management are key goals for the success
of modern battery-supplied multimedia devices. This kind of devices are
usually based on SoCs with a wide range of subsystems, that compete in
the usage of shared resources, and offer several power saving capabilities,
but need an adequate software support to exploit such capabilities.
In this paper we present Constrained Power Management (CPM), a
cross-layer formal model and framework for power and resource management,
targeted to MPSoC-based devices. CPM allows coordination
and communication, among applications and device drivers, to reduce
energy consumption without compromising QoS. A dynamic and multiobjective
optimization strategy is supported, which has been designed to
have a negligible overhead on the development process and at run-time.
1 Introduction
New generation of mobile devices are usually based on platforms using a Multi-
Processor System-on-Chip (MPSoC) which is composed of many subsystems and
surrounded by a broad set of peripherals. Each subsystem is typically characterized
by several working modes (WMs), with corresponding different levels
of Quality-of-Service (QoS) provided and power consumptions profiles. Modern
hardware technologies increased the capability to reduce both dynamic and static
power consumptions [1]. However, several mechanisms to save power at circuit
level require an adequate software support to be effectively exploited. Indeed,
to properly satisfy applications’ QoS demands it is required to track system resources
availability and usage which directly impact on energy consumptions.
Moreover the need for support of heterogeneous usage scenarios makes the management
of resources and power saving a challenging design goal.
This work introduce the general idea behind the definition of a system-wide
power and performances optimization strategy, to be implemented at OS level.
This solution has been designed to be sufficiently portable among different platforms,
without compromising too much its accuracy and efficiency, and easily
adapt to all possible different device usage scenarios. We prove that a hierarchical
C. Müller-Schloer, W. Karl, and S. Yehia (Eds.): ARCS 2010, LNCS 5974, pp. 37–48, 2010.
c○ Springer-Verlag Berlin Heidelberg 2010