EqualWrites: Reducing Intra-set Write Variations for Enhancing Lifetime of Non-volatile Caches

Journal Article · Thu Jan 29 00:00:00 EST 2015 · IEEE Transactions on Very Large Scale Integration (VLSI) Systems

DOI:https://doi.org/10.1109/TVLSI.2015.2389113· OSTI ID:1265263

Mittal, Sparsh ^[1]; Vetter, Jeffrey S. ^[1]

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1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Driven by the trends of increasing core-count and bandwidth-wall problem, the size of last level caches (LLCs) has greatly increased and hence, the researchers have explored non-volatile memories (NVMs) which provide high density and consume low-leakage power. Since NVMs have low write-endurance and the existing cache management policies are write variation-unaware, effective wear-leveling techniques are required for achieving reasonable cache lifetimes using NVMs. We present EqualWrites, a technique for mitigating intra-set write variation. In this paper, our technique works by recording the number of writes on a block and changing the cache-block location of a hot data-item to redirect the future writes to a cold block to achieve wear-leveling. Simulation experiments have been performed using an x86-64 simulator and benchmarks from SPEC06 and HPC (high-performance computing) field. The results show that for single, dual and quad-core system configurations, EqualWrites improves cache lifetime by 6.31X, 8.74X and 10.54X, respectively. In addition, its implementation overhead is very small and it provides larger improvement in lifetime than three other intra-set wear-leveling techniques and a cache replacement policy.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1265263
• Journal Information: IEEE Transactions on Very Large Scale Integration (VLSI) Systems, Vol. 24, Issue 1; ISSN 1063-8210
• Publisher: IEEE
• Country of Publication: United States
• Language: English

Related Subjects

97 MATHEMATICS AND COMPUTING
Cache memory
device lifetime
intra-set write variation (WV)
non-volatile memory (NVM or NVRAM)
wear leveling