The betrayal of constant power × time: Finding the missing joules of transiently-powered computers

The betrayal of constant power × time : Finding the missing joules of transiently-powered computers

Transiently-powered computers (TPCs) lay the basis for a battery-less Internet of Things, using energy harvesting and small capacitors to power their operation. This power supply is characterized by extreme variations in supply voltage, as capacitors charge when harvesting energy and discharge when computing. We experimentally find that these variations cause marked fluctuations in clock speed and power consumption, which determine energy efficiency. We demonstrate that it is possible to accurately model and concretely capitalize on these fluctuations. We derive an energy model as a function of supply voltage and develop EPIC, a compile-time energy analysis tool. We use EPIC to substitute for the constant power assumption in existing analysis techniques, giving programmers accurate information on worst-case energy consumption of programs. When using EPIC with existing TPC system support, run-time energy efficiency drastically improves, eventually leading up to a 350% speedup in the time to complete a fixed workload. Further, when using EPIC with existing debugging tools, programmers avoid unnecessary program changes that hurt energy efficiency.

TEKNIK OCH TEKNOLOGIER Elektroteknik och elektronik Datorsystem hsv//swe
ENGINEERING AND TECHNOLOGY Electrical Engineering, Electronic Engineering, Information Engineering Computer Systems hsv//eng
Energy modelling
Intermittent computing
Transiently powered computers
Embedded systems
Energy harvesting
Energy utilization
Program compilers
Program debugging
Analysis techniques
Constant power
Debugging tools
Harvesting energies
Supply voltages
System supports
Energy efficiency

Bakar, A.Lahore University of Management Sciences, Pakistan (author)
Bhatti, NaveedRISE,SICS (author)
Alizai, MLahore University of Management Sciences, Pakistan (author)
Siddiqui, J. H.Lahore University of Management Sciences, Pakistan (author)
Mottola, LucaRISE,SICS,Politecnico di Milano, Italy; RI.SE SICS Sweden(Swepub:uu)lucmo115 (author)
Lahore University of Management Sciences, PakistanSICS (creator_code:org_t)

In:Proceedings of the ACM SIGPLAN Conference on Languages, Compilers, and Tools for Embedded Systems (LCTES)New York, NY, USA : Association for Computing Machinery, s. 97-1099781450367240

By the author/editor: Ahmed, Saad; Bakar, A.; Bhatti, Naveed; Alizai, M; Siddiqui, J. H.; Mottola, Luca

About the subject

ENGINEERING AND TECHNOLOGY: ENGINEERING AND ...; and Electrical Engin ...; and Computer Systems

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