Limited endurance problem and low cell reliability are main challenges of phase change memory (PCM) as an alternative to DRAM. To further prolong the lifetime of a PCM device, there exist a number of techniques that can be grouped in two categories: 1) reducing the write rate to PCM cells, and 2) handling cell failures when faults occur. Our experiments confirm that during write operations, an extensive non-uniformity in bit flips is exhibited. To reduce this nonuniformity, we present byte-level shifting scheme (BLESS) which reduces write pressure over hot cells of blocks. Additionally, this shifting mechanism can be used for error recovery purpose by using the MLC capability of PCM and manipulating the data block to recover faulty cells. Evaluation results for multi-threaded workloads reveal 14-25% improvement in lifetime over existing state-of-the-art schemes.
Hamid Sarbazi-Azad received his BSc in electrical and computer engineering from Shahid-Beheshti University, Tehran, Iran, in 1992, his MSc in computer engineering from Sharif University of Technology, Tehran, Iran, in 1994, and his PhD in computing science from the University of Glasgow, Glasgow, UK, in 2002. He is currently a professor in the department of computer engineering at Sharif University of Technology, and heads the School of Computer Science, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran. His research interests include high-performance computer/memory architectures, NoCs and SoCs, parallel and distributed systems, performance modelling/evaluation, and storage systems, on which he has published about 300 refereed conference and journal papers. He received Khwarizmi International Award in 2006, TWAS Young Scientist Award in engineering sciences in 2007, and Sharif University Distinguished Researcher awards in years 2004, 2007, 2008, 2010, and 2013. He is a member of managing board of Computer Society of Iran (CSI), and has served as the editor-in-chief for the CSI Journal on Computer Science and Engineering, an associate editor for IEEE Transactions on Computers and ACM Computing Surveys, and editorial board member for Elsevier’s Computers & Electrical Engineering journal, International Journal of Computers & Applications, and Journal of Parallel and Distributed Computing and Networks.
