Publications

ACM International Conference Proceeding Series

Awad, Amro A.; Hammond, Simon D.; Hughes, Clayton H.; Rodrigues, Arun; Hemmert, Karl S.; Hoekstra, Robert J.

DRAM scalability is becoming more challenging, pushing the focus of the research community towards alternative memory technologies. Many emerging non-volatile memory (NVM) devices are proving themselves to be good candidates to replace DRAM in the coming years. For example, the recently announced 3D-XPoint memory by Intel/Micron promises latencies that are comparable to DRAM, while being non-volatile and much more dense. While emerging NVMs can be fabricated in different form factors, the most promising (from a performance perspective) are NVM-based DIMMs. Unfortunately, there is a shortage of studies that explore the design options for NVM-based DIMMs. Because of the read and write asymmetries in both power consumption and latency, as well as limited write endurance, which often requires wear-leveling techniques, NVMs require a specialized controller. The fact that future on-die memory controllers are expected to handle different memory technologies pushes future hardware towards on-DIMM controllers. In this paper, we propose an architectural model for NVM-based DIMMs with internal controllers, explore their design space, evaluate different optimizations and reach out to several architectural suggestions. Finally, we make our model publicly available and integrate it with a widely used architectural simulator.

Awad, Amro A.; Voskuilen, Gwendolyn R.; Rodrigues, Arun; Hammond, Simon D.; Hoekstra, Robert J.; Hughes, Clayton H.

DRAM technology is the main building block of main memory, however, DRAM scaling is becoming very challenging. The main issues for DRAM scaling are the increasing error rates with each new generation, the geometric and physical constraints of scaling the capacitor part of the DRAM cells, and the high power consumption caused by the continuous need for refreshing cell values. At the same time, emerging Non- Volatile Memory (NVM) technologies, such as Phase-Change Memory (PCM), are emerging as promising replacements for DRAM. NVMs, when compared to current technologies e.g., NAND-based ash, have latencies comparable to DRAM. Additionally, NVMs are non-volatile, which eliminates the need for refresh power and enables persistent memory applications. Finally, NVMs have promising densities and the potential for multi-level cell (MLC) storage.