Ezra's Round Table / Systems Seminar: José F. Martínez (Cornell ECE) - Can Your Local Farmer’s Market Help Your CPU Performance?

Description

Efficiently allocating shared on-chip resources across cores is critical to optimizing execution in chip multiprocessors (CMPs). Techniques proposed in the literature often rely on global, centralized mechanisms that seek to maximize system throughput. However, global optimization may hurt scalability: as more cores are integrated on a die, the search space grows exponentially, making it harder to achieve optimal or even acceptable operating points at run-time without incurring significant overheads.

I will present XChange, a novel CMP resource allocation mechanism based on market theory that delivers scalable high throughput and fairness. Through XChange, the CMP functions as a market, where each shared resource is assigned a price which changes over time, and each core seeks to maximize its own utility, by bidding for these shared resources. Because each core works largely independently, the resource allocation becomes a scalable, mostly distributed decision-making process. In addition, by distributing the resources proportionally to the bids, the system avoids unfairness, treating each core in an unbiased manner.

Our evaluation shows that, using detailed simulations of a 64-core CMP configuration running a variety of multiprogrammed workloads, the proposed XChange mechanism improves system throughput (weighted speedup) by about 21% on average, and fairness (harmonic speedup) by about 24% on average, compared with equal-share on-chip cache and power distribution. On both metrics, that is at least about twice as much improvement as a state-of-the-art centralized allocation scheme. Furthermore, our results show that XChange is significantly more scalable than the state-of-the-art centralized allocation scheme we compare against.

Bio: José Martínez is professor of electrical and computer engineering, and member of the computer science and systems engineering graduate fields at Cornell. His research work has earned several awards; among them: two IEEE Micro Top Picks papers; an HPCA Best Paper award; Best Paper nominations at MICRO and HPCA; an NSF CAREER award; two IBM Faculty awards; and one of the inaugural UIUC Computer Science Outstanding Educator Alumnus awards. On the teaching side, he has been recognized with one Dorothy & Fred Chau M.S. ’74 and two Kenneth A. Goldman '71 College teaching awards; a Ruth and Joel Spira Teaching Excellence award; as the most influential college professor of Merrill Presidential Scholars Andrew Tibbits (2007) and Gulnar Mirza (2016); and as the 2011 Professor of the Year by the Tau Beta Pi Engineering Honor Society.