Category Archives: Publication

New paper published: “Against the Current: Introducing Reversibility to Superscalar Processors via Reversible Branch Predictors”

tlab PhD student Byron Gregg presented both a paper and a poster on “Against the Current: Introducing Reversibility to Superscalar Processors via Reversible Branch Predictors” at “The 15th International Green and Sustainable Computing Conference,” Austin, TX, 2024.

IGSCC proceedings: https://www.computer.org/csdl/proceedings/igsc/2024/22gEnJUWwMg 

Citation:

B. Gregg and C. Teuscher, “Against the Current: Introducing Reversibility to Superscalar Processors via Reversible Branch Predictors,” 2024 IEEE 15th International Green and Sustainable Computing Conference (IGSC), Austin, TX, USA, 2024, pp. 135-141, doi: 10.1109/IGSC64514.2024.00033.

Abstract:

Although highly energy efficient, adiabatic and reversible systems suffer from performance drawbacks inherent to the physical operations that make them so efficient. Superscalar processors provide high performance through out-of-order speculative work of which an effective branch predictor is a key component in those performance gains. In the context of reversibility, a branch predictor is a design focal point because any fully reversible system must also be able to predict branch outcomes when in reverse mode. Taking advantage of Temporal Streaming techniques, this paper introduces several reversible branch predictor implementations which enable reversible and out-of-order instruction execution. These first-of-their-kind designs allow for a superscalar architecture that would maintain both a high level of performance and a high level of energy efficiency with the ability to un-compute obsolete data stored in memory. Testing our designs using the SimpleScalar out-of-order simulator, we estimate possible additional savings of 24 fJ per MB of data recovered at room temperature and at reverse prediction rates 2.27% higher than the forward. This work opens new avenues for designing and developing what we are calling Fully Adiabatic, Reversible, and Superscalar (FARS) Processor Architectures and is the first of many adaptations of conventional superscalar components to a reversible system.

Summer interns publish book

Students of the NSF Research Experience for Undergraduates (REU) on “Computational Modeling Serving Portland,” the altREU program to “Design, Program, and Use Computers to Benefit Society,” and teuscher.:Lab interns edited and published a 300-page book on their summer research projects. The book publishing project was entirely led by the interns. The book can be ordered on Amazon (all benefits go to a good cause) at https://www.amazon.com/dp/B0DJ5C1VMN or downloaded for free on PDXScholar at https://archives.pdx.edu/ds/psu/42556.

Dr. Teuscher presents at the 2024 Annual Conference of the American Society for Engineering Education (ASEE)

Dr. Teuscher presents a paper on the altREU program at the 2024 Annual Conference of the American Society for Engineering Education (ASEE), which was held in Portland, OR, Jun 23-26, 2024.


M. Gray, E. Shortlidge, and C. Teuscher, altREU: An Alternative Online Research Experience Broadens Opportunities for Undergraduates, Proceedings of the 2024 Annual Conference of the American Society for Engineering Education (ASEE), Portland, OR, Jun 23-26.

Abstract: 

Promoting undergraduate students’ persistence in Science, Technology, Engineering, and Mathematics (STEM) fields is critical for meeting national calls to strengthen the future STEM workforce. National data has shown that of all students who enter a STEM degree program, less than 40% earn a STEM degree within six years. Calls have been made to produce an additional one million STEM professionals to maintain the countries’ relevance in these fields, thus an annual increase in the number of students who graduate with a STEM degree is required to meet this demand. These calls also emphasize the need to increase graduation rates for students belonging to groups that are underrepresented in STEM, as they currently leave STEM majors at higher rates than their represented peers. Undergraduate research experiences are frequently implicated as a means for increasing interest in STEM fields and STEM graduate programs, and are correlated to students persisting to graduation. While research experiences can positively influence persistence in STEM fields, there are inequities in who gets to participate in these experiences. The limited number of undergraduate research opportunities available and the structure of the selection process can contribute to existing inequities.
In Spring 2020, the COVID-19 pandemic forced universities to quickly move to remote instruction. In response, we created the altREU program, a fully online research experience for undergraduate students to continue to provide students with opportunities to conduct meaningful research and develop critical skills during this time.
Here we describe the ‘alternative’ Research Experience for Undergraduates (altREU) model and report on student experiences in this online research program. In 2020, sixteen students from US institutions participated in the program. The altREU program was designed to attract research-interested students and to broaden participation in undergraduate research. To understand the student’s experiences, we collected observations and conducted exit interviews. Twelve of the sixteen students successfully completed the altREU program. Overall, the participants expressed that the online nature of the altREU program did not, to their knowledge, impact their ability to successfully conduct research. Our findings suggest that online research programs may provide a comparable experience to in-person research programs, with the added benefit of potentially reducing barriers that students may face to accessing in-person research opportunities. This paper summarizes the design of the program and gives suggestions for fully online research participation based on program assessment and student feedback. We believe that the altREU model can be relatively easily replicated across institutions.

Paper download: https://nemo.asee.org/public/conferences/344/papers/41908/view

NANOARCH 2023 paper + presentation

Dr. Teuscher presented his paper on “Material and Physical Reservoir Computing for Beyond CMOS Electronics: Quo Vadis?” at the 18th ACM International Symposium on Nanoscale Architectures (NANOARCH 23), which was held in Dresden, Germany, Dec 18-20, 2023.