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

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