Research Problems and Opportunities in Memory Systems

Abstract

The memory system is a fundamental performance and energy bottleneck
in almost all computing systems. Recent system design, application,
and technology trends that require more capacity, bandwidth,
efficiency, and predictability out of the memory system make it an
even more important system bottleneck. At the same time, DRAM
technology is experiencing difficult {\em technology scaling}
challenges that make the maintenance and enhancement of its capacity,
energy-efficiency, and reliability significantly more costly with
conventional techniques.

In this article, after describing the demands and challenges faced by
the memory system, we examine some promising research and design
directions to overcome challenges posed by memory
scaling. Specifically, we describe three major {\em new} research
challenges and solution directions: 1) enabling new DRAM
architectures, functions, interfaces, and better integration of the
DRAM and the rest of the system (an approach we call {\em system-DRAM                          co-design}), 2) designing a memory system that employs emerging
non-volatile memory technologies and takes advantage of multiple
different technologies (i.e., {\em hybrid memory systems}), 3)
providing predictable performance and QoS to applications sharing the
memory system (i.e., {\em QoS-aware memory systems}). We also briefly
describe our ongoing related work in combating scaling challenges of
NAND flash memory.