Afternoon Tutorial 2: Caches in the Modern Memory Hierarchy with Persistent Memory and Flash

Monday, February 25, 2019 - 1:30 pm5:00 pm

Constitution Ballroom B

Irfan Ahmad, CachePhysics, and Ymir Vigfusson, Emory University


For a very long time, practical scaling of every level in the computing hierarchy has required innovation and improvement in caches. This is as true for CPUs as it is for storage and networked, distributed systems. As such, research into cache efficiency and efficacy improvements has been highly motivated and continues with strong improvements to this day. However, there are certain areas in cache algorithms optimization that have only recently experienced breakthroughs.

In this tutorial, we will start by reviewing the history of the caching algorithm research and practice in industry. Of particular interest to us are multi-tier memory hierarchies that are getting more complex and deep due to hardware innovations. These hierarchies motivate revisiting multi-tier algorithms. We will then review key tools in the research or and management called cache utility curves and recent literature that has made them easier to compute. Using this tool, we will excavate around caching policies and their trade-offs. We will also spend some time thinking about optimality for caches in modern memory hierarchies with DRAM, non-volatile/persistent memory and flash.

Topics include:

  • Overview and history of the caching algorithm research and practice in industry
  • Introduction to new challenges posed by multi-tier memory hierarchies
  • Review of Cache utility curves and recent literature
  • Experimenting with caching policies for production uses cases
  • How to find the optimal cache

Irfan Ahmad, CachePhysics

Irfan Ahmad is the CEO and Cofounder of CachePhysics. Previously, he served as the CTO of CloudPhysics, pioneer in SaaS Virtualized IT Operations Management, which he cofounded in 2011. Irfan was at VMware for nine years, where he was R&D tech lead for the DRS team and co-inventor for flagship products including Storage DRS and Storage I/O Control. Before VMware, Irfan worked on the Crusoe software microprocessor at Transmeta.

Irfan is an inventor on more than 35 patents. He has published at ACM SOCC, FAST, USENIX ATC, and IEEE IISWC, including two Best Paper Awards. Irfan has chaired HotStorage, HotCloud and VMware’s R&D Innovation Conference. He serves on steering committees for HotStorage, HotCloud, and HotEdge. Irfan has served on program committees for USENIX ATC, FAST, MSST, HotCloud, and HotStorage, among others, and as a reviewer for the ACM Transactions on Storage.

Ymir Vigfusson, Emory University

Ymir Vigfusson is Assistant Professor of Mathematics and Computer Science at Emory University since 2014, Adjunct Assistant Professor at the School of Computer Science at Reykjavik University since 2011, and a co-founder and Chief Science Officer of the offensive security company Syndis since 2013. Ymir completed his Ph.D. in Computer Science at Cornell University in 2010 where his dissertation on "Affinity in Distributed Systems" was nominated for the ACM Doctoral Dissertation Award.

His primary research interests are on distributed systems and caching, having worked on cache replacement in the IBM Websphere eXtreme Scale at IBM Research (2009–2011), and more recently as part of his NSF CAREER program on "Rethinking the Cache Abstraction." He has published at conferences that include ACM SOCC, USENIX ATC, VLDB, and EuroSys, as well as ACM TOCS. Ymir serves on the steering committee of LADIS (2010–2018), has been on program committees for ACM SOCC, ICDCS, EuroSys, and P2P. In addition to caching, Ymir also works on improving epidemiological surveillance and information security, funded by the Center for Disease Control and grants from the Icelandic Center for Research.

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