Your Abstractions are Worth^H^H^H^H^HPowerless! Non-Volatile Storage and Computation on Embedded Devices* (*Batteries Not Included)
Speaker: Kevin Fu, University of Massachusetts
Location: Warren Weaver Hall 1302
Date: December 2, 2011, 11:30 a.m.
Host: Helen Nissenbaum
Did you hear the one about how many batteries it takes to turn on a Turing machine? None! It's outside the model of computation. Yet it's extremely difficult to store information or compute without power. Perpetual computing is hard. As embedded systems continue to shrink in size and energy consumption, the battery becomes the greatest bottleneck. I will describe recent research results on batteryless, RFID-scale computers: the UMass Moo platform, stochastic storage on Half-Wits (USENIX FAST), and energy-aware checkpoints with Mementos (ACM ASPLOS).
The UMass Moo platform behaves like an RFID tag with non-volatile memory, sensing, radio communication, and von Neumann-style computation. Based on the Intel WISP, this batteryless device relies on RF energy harvesting and a capacitor that stores eight orders of magnitude less energy than a typical AA battery. This lack of energy leads to two research challenges: how to reliably store data in non-volatile memory at low cost and low voltage, and how to compute when power losses interrupt programs every few hundred milliseconds.
The Half-Wits work analyzes the stochastic behavior of writing to embedded flash memory at voltages lower than recommended by a microcontroller's specifications to reduce energy consumption. Flash memory integrated within a microcontroller typically requires the entire chip to operate on common supply voltage almost double what the CPU portion requires. Our approach tolerates a lower supply voltage so that the CPU operates in an energy proportional manner. Our software-only coding algorithms enable reliable storage at low voltages on unmodified hardware by exploiting the electrically cumulative nature of half-written data in write-once bits (half-wits). Measurements show that our software approach reduces energy consumption by up to 50%. This work is joint with Erik Learned-Miller (UMass Amherst) and Andrew Jiang (Texas A&M;).
Transiently powered computers risk the frequent, complete loss of volatile memory. Mementos automatically instruments programs with energy-aware checkpoints to protect RAM and registers. A suite of compile- and run-time tools help to transform long-running programs into interruptible computations. The contributions include a study of the run-time environment for programs on RFID-scale devices, an energy-aware state checkpointing system for MSP430 family of microcontrollers, and a trace-driven simulator of transiently powered RFID-scale devices. This work is joint with Jacob Sorber (Dartmouth College).
Kevin Fu is an Associate Professor of Computer Science and adjunct Associate Professor of Electrical & Computer Engineering at the University of Massachusetts Amherst. Prof. Fu makes embedded computer systems smarter: better security and safety, reduced energy consumption, faster performance. Prof. Fu is a visiting scientist at the Food & Drug Administration, the Beth Israel Deaconess Medical Center of Harvard Medical School, and the MIT Computer Science and Artificial Intelligence Lab. He is an incoming member of the NIST Information Security and Privacy Advisory Board. Prof. Fu received a Sloan Research Fellowship, NSF CAREER award, and best paper awards from various fine academic silos of computing. He was named MIT Technology Review TR35 Innovator of the Year.
His most recent contributions on trustworthy medical devices and computational RFIDs appear in ACM, IEEE, and USENIX computing venues as well as cardiovascular venues and the Institute of Medicine. Prof. Fu innovates technology such as low-voltage flash memory, batteryless computers, and secure file systems. Prof. Fu's contributions also include numerous case studies that analyze the causal factors lurking behind security failures: wirelessly inducing ventricular fibrillation in an implantable cardiac defibrillator, self-compromising automatic updates to anti-virus software, skimming contactless credit cards through clothing, and circumventing creative cryptography in access-controlled websites. His research is featured in critical articles by the NYT, WSJ, and NPR.
Prof. Fu received his Ph.D. in Electrical Engineering and Computer Science from MIT when his research pertained to secure storage and web authentication. He also holds a certificate of achievement in artisanal bread making from the French Culinary Institute and an unofficial minor in Latin.
URLs: http://spqr.cs.umass.edu/ http://omdrl.org/ http://secure-medicine.org/ http://sharps.org/
Refreshments will be offered starting 15 minutes prior to the scheduled start of the talk.