STT-RAM memory hierarchy designs aimed to performance, reliability and energy consumption

Abstract

Current applications demand larger on-chip memory capacity since off-chip memory accesses be-come a bottleneck. However, if we want to achieve this by scaling down the transistor size of SRAM-based Last-Level Caches (LLCs) it may become prohibitive in terms of cost, area and en-ergy. Therefore, other technologies such as STT-RAM are becoming real alternatives to build the LLC in multicore systems. Although STT-RAM bitcells feature high density and low static power, they suffer from other trade-offs. On the one hand, STT-RAM writes are more expensive than STT-RAM reads and SRAM writes. In order to address this asymmetry, we will propose microarchitectural techniques to minimize the number of write operations on STT-RAM cells. On the other hand, reliability also plays an important role. STT-RAM cells suffer from three types of errors: write, read disturbance, and retention errors. Regarding this, we will suggest tech-niques to manage redundant information allowing error detection and information recovery.

Postprint (published version)