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PPoPP 2021
Sat 27 February - Wed 3 March 2021

Day 1: March 1, 2021 (Monday)

Speaker: Maurice Herlihy (Brown University)
Title: Atomicity without Trust

There is increasing interest in distributed systems where partici- pants stand to benefit from cooperation, but do trust one another not to cheat. Although blockchain-based commerce is perhaps the most visible example of such systems, the problem of economic exchange among mutually untrusting autonomous parties is a fundamental one independent of particular technologies.

This talk argues that such systems require rethinking our notions of correctness for distributed concurrency control and fault-tolerance. Addressing this challenge brings up questions familiar from classical distributed systems: how to combine multiple steps into a single atomic action, how to recover from failures, and how to coordinate concurrent access to data. Commerce among untrusting parties is a kind of fun-house mirror of classical distributed computing: familiar features are recognizable, but distorted. For example, classical atomic transac- tions are often described in terms of the well-known ACID properties: atomicity, consistency, isolation, and durability. We will see that untrusting cooperation requires structures superficially similar to, but fundamentally different from, classical atomic transactions.

Maurice Herlihy has an A.B. in Mathematics from Harvard University, and a Ph.D. in Computer Science from M.I.T. He has served on the faculty of Carnegie Mellon University and the staff of DEC Cambridge Research Lab. He is the recipient of the 2003 Dijkstra Prize in Distributed Computing, the 2004 Gödel Prize in theoretical computer science, the 2008 ISCA influential paper award, the 2012 Edsger W. Dijkstra Prize, and the 2013 Wallace McDowell award. He received a 2012 Fulbright Distinguished Chair in the Natural Sciences and Engineering Lecturing Fellowship, and he is fellow of the ACM, a fellow of the National Academy of Inventors, the National Academy of Engineering, and the National Academy of Arts and Sciences.

Day 2: March 2, 2021 (Tuesday)

Speaker: Mary Hall (University of Utah)
Title: Data Layout and Data Representation Optimizations to Reduce Data Movement

Code generation and optimization for the diversity of current and future architectures must focus on reducing data movement to achieve high performance. How data is laid out in memory, and representations that compress data (e.g., reduced floating point precision) have a profound impact on data movement. Moreover, the cost of data movement in a program is architecture-specific, and consequently, optimizing data layout and data representation must be performed by a compiler once the target architecture is known. With this context in mind, this talk will provide examples of data layout and data representation optimizations, and call for integrating these data properties into code generation and optimization systems.

Mary Hall is a Professor and Director of the School of Computing at University of Utah. She received a PhD in Computer Science from Rice University. Her research focus brings together compiler optimizations targeting current and future high-performance architectures on real-world applications. Hall’s prior work has developed compiler techniques for exploiting parallelism and locality on a diversity of architectures: automatic parallelization for SMPs, superword-level parallelism for multimedia extensions, processing-in-memory architectures, FPGAs and more recently many-core CPUs and GPUs. Professor Hall is an IEEE Fellow, an ACM Distinguished Scientist and a member of the Computing Research Association Board of Directors. She actively participates in mentoring and outreach programs to encourage the participation of women and other groups underrepresented in computer science.

Day 3: March 3, 2021 (Wednesday)

Speaker: Nam Sung Kim (University of Illinois at Urbana-Champaign / Samsung Electronics)
Title: A Journey to a Commercial-Grade Function-In-Memory (FIM) Chip Development

Emerging applications demand high off-chip memory bandwidth, but it becomes very expensive to further increase the bandwidth of off-chip memory under stringent physical constraints of chip packages and system boards. Besides, energy efficiency of moving data across the memory hierarchy of processors has steadily worsened with the stagnant technology scaling and poor data reuse characteristics of the emerging applications. To cost-effectively increase the bandwidth and energy efficiency, researchers began to reconsider the past processing-in-memory (PIM) architectures and advance them further, especially with recent integration technologies such as 2.5D/3D stacking. Albeit the recent advances, no major memory manufacturer had developed even a proof-of-concept silicon yet, not to mention a product.

In this talk, I will start with discussing various practical and technical challenges that have been overlooked by researchers and prevented the industry from successfully commercializing PIM. Elegantly tackling the challenges, I first coined a concept of FIM as an alternative to PIM. Subsequently, I led the development of a commercial-grade FIM chip, which was fabricated by a major DRAM manufacturer for the first time and successfully integrated with unmodified commercial processors. I will present this journey in this talk.

Nam Sung Kim is a Senior Vice President at Samsung Electronics as well as a Professor at the University of Illinois. At Samsung he led the architecture definitions and designs of next generation DRAM devices including HBM, LPDDR, DDR, and GDDR. He has published more than 200 refereed articles to highly-selective conferences and journals in the field of circuit, architecture, and computer-aided design. For his contributions to developing power-efficient computer architectures, he was elevated to IEEE and ACM Fellows in 2016 and 2021, respectively, and received the ACM SIGARCH/IEEE-CS TCCA Influential ISCA Paper Award in 2017. He is also a hall of fame member of all three major computer architecture conferences, ISCA, MICRO, and HPCA.