From Thermodynamically-Aware Probabilistic Algorithms to Ultra-Low Energy CMOS Computing Platforms

PROF. KRISHNA PALEM,
Georgia Institute of TechnologyGerontology Auditorium (GER-124)Tuesday, November 16, 20043:00-4:00p.m.(A reception will follow the seminar at 4:00p.m.)Abstract:The energy consumed by computations is a significant concern, especially within the context of embedded systems, on par with the past focus on raw speed or its derivative, performance in the high-performance computing domain. In this talk, we will outline an entirely new approach to energy-aware computing: trading the probability of the BIT being correct for savings in the energy consumed, yielding a probabilistic bit or PBIT (instead of a conventional BIT which is guaranteed to be correct). At its heart, the approach taken here is built on the fundamental and novel thesis that the energy consumed by a computation is proportional to the associated accuracy, characterized as the probability of being correct, with which each "bit'' is computed. With this as background, probabilistic hardware devices---these can be viewed as the "hardware'' counterparts of the well-known probabilistic algorithms---and gates realized from conventional CMOS technology for computing PBITs will be described. Our probabilistic devices are constructed through the counterintuitive approach of using noise, which is increasingly being viewed as a hurdle to sustaining Moore's law, as a resource rather than as an impediment. Specifically, we have demonstrated that coupling thermally induced sources of noise, as well as the prevalent power-supply noise with a conventional CMOS device yields a probabilistic switch, which can in turn be a basis for realizing probabilistic applications in silicon. These probabilistic (hardware) switches compute with a definite probability of error, and have been demonstrated to serve as natural building-blocks in architectures for supporting probabilistic algorithms, yielding significant savings to the (energy x performance) metric in a variety of embedded computing applications ranging over speech and pattern recognition, robotics and others---improvements of over a factor of 100 within the context of an AMI 0.5µm, a TSMC 0.25µm and proprietary deep submicron processes, when compared to executing the same applications on a low energy embedded processor, the StrongARM SA-1100. At a deeper level, all of this work rests on the twin foundations of classical thermodynamics (of Maxwell, Boltzmann and Gibbs), and the relatively modern computational complexity theory. Time permitting, these foundations will be surveyed.Bio:Krishna V. Palem holds Professorships with tenure in Electrical and Computer Engineering and in Computer Science in the College of Computing, a senior research leadership in the College of Engineering, and has been the founding director of the Center for Research in Embedded Systems and Technology (CREST) (www.crest.gatech.edu) at the Georgia Institute of Technology, since 1999. Over the years, he has played an active role in enabling a community of research in embedded and hybrid systems internationally through invited and keynote lectures, conference organization and participation as well as editorial contributions to journals. Among others, he serves on the editorial board of the newly created ACM Transactions on Embedded Computing Systems. Notably, he has chaired bodies whose advise has led to funding initiatives in Embedded and Hybrid Systems by the National Science Foundation in the U.S., as well as by the leading research funding agency A*Star of Singapore. With Guang Gao, he started the Compilers, Architectures and Synthesis for Embedded Systems (CASES) workshop series in 1998. Since then, this workshop has blossomed into a thriving international conference sponsored by ACM SIGs, serving the community as a point of focus for top quality research, driven exclusively by concerns of the embedded computing domain. From 1986 to 1994, Palem was a member of the IBM T. J. Watson research center. During this period, he also served as an Advanced Technology Consultant to IBM's Santa Teresa Laboratory and helped with the transfer of research technology including his own, into compilers for IBM's RS6000 line of processors. He was a Schonbrunn visiting professor at the Hebrew University of Jerusalem, Israel, where he was recognized for excellence in teaching, and has held visiting positions at the National University and Nanyang Technological University, of Singapore. He is a fellow of the IEEE.Host: Prof. Viktor Prasanna, x04483

Location: Ethel Percy Andrus Gerontology Center (GER) - -124

Audiences: Everyone Is Invited

Contact: Rosine Sarafian