Leakage Aware Hardware Architecture and Dynamic Power Scheduling
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Date
2011-07
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Addis Ababa University
Abstract
In the last couple of decades, battery powered mobile devices such as smart phones have become
one of the most prolific electronic devices in history. With this has come an exploding demand
for performance and features that cover almost every aspect of our digital multimedia
interconnected lives including 3-D gaming, still and video cameras, WAN, Bluetooth, highspeed
data connections, and so on. As ever increasing features continue to be integrated into
these products, there is an ongoing need to develop innovative ways to reduce power
consumption and extend battery life.
A core requirement of effective and efficient management of energy is a good understanding of
where and how the energy is used: how much of the system’s energy is consumed by which parts
of the system and under what circumstances.
In this work, a Smartphone is developed, hereafter referred to as the XLP, from the ground up
with modular architecture where each module is supplied through an active switch matrix which
is memory mapped and updated periodically by the main applications processor in the system.
The basic notion of this architecture is achieving zero-leakage power for modules which are not
being used. This significantly reduces the idle power consumption which accounts for more than
60% of the average power consumed in smart phones. In addition to this novel approach on the
hardware architecture, a stochastic dynamic power scheduling and on-demand power and clock
gating policies are developed. A number of possible policies are presented and, under given
conditions, one of them is proved to be optimal using the energy response time product (ERP)
metrics.
The XLP is compared with three commercial smart phones, Openmoko Freerunner, HTC Dream
and Google’s Nexus One on similar tests and usage scenarios. The XLP and all these three
devices use the ARM microprocessor and run the Linux kernel. The comparison is on
performance and power consumption. The XLP is proved to have the lowest power consumption
on competitive performance levels.
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Keywords
Hardware, Architecture