EqualWrites: Reducing Intra-Set Write Variations for Enhancing Lifetime of Non-Volatile Caches

Sparsh Mittal; Jeffrey S. Vetter

doi:10.1109/TVLSI.2015.2389113

EqualWrites: Reducing Intra-Set Write Variations for Enhancing Lifetime of Non-Volatile Caches

Sparsh Mittal, Jeffrey S. Vetter

Computer Science and Mathematics Div

Research output: Contribution to journal › Article › peer-review

24 Scopus citations

Abstract

Driven by the trends of increasing core-count and bandwidth-wall problem, the size of last level caches has greatly increased, and hence the researchers have explored non-volatile memories (NVMs) that provide high density and consume low-leakage power. Since NVMs have low write endurance and the existing cache management policies are write variation (WV) unaware, effective wear-leveling techniques (WLTs) are required for achieving reasonable cache lifetimes using NVMs. We present EqualWrites, a technique for mitigating intra-set WV. 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 high-performance computing field. The results show that for single-, dual-, and quad-core system configurations, EqualWrites improves cache lifetime by 6.31×, 8.74×, and 10.54×, respectively. In addition, its implementation overhead is very small and it provides larger improvement in lifetime than three other intra-set WLTs and a cache replacement policy.

Original language	English
Article number	7027229
Pages (from-to)	103-114
Number of pages	12
Journal	IEEE Transactions on Very Large Scale Integration (VLSI) Systems
Volume	24
Issue number	1
DOIs	https://doi.org/10.1109/TVLSI.2015.2389113
State	Published - Jan 2016

Funding

This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doepublic-access-plan).

Funders	Funder number
DOE Public Access Plan
United States Government
U.S. Department of Energy

Keywords

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

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10.1109/TVLSI.2015.2389113

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title = "EqualWrites: Reducing Intra-Set Write Variations for Enhancing Lifetime of Non-Volatile Caches",

abstract = "Driven by the trends of increasing core-count and bandwidth-wall problem, the size of last level caches has greatly increased, and hence the researchers have explored non-volatile memories (NVMs) that provide high density and consume low-leakage power. Since NVMs have low write endurance and the existing cache management policies are write variation (WV) unaware, effective wear-leveling techniques (WLTs) are required for achieving reasonable cache lifetimes using NVMs. We present EqualWrites, a technique for mitigating intra-set WV. 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 high-performance computing field. The results show that for single-, dual-, and quad-core system configurations, EqualWrites improves cache lifetime by 6.31×, 8.74×, and 10.54×, respectively. In addition, its implementation overhead is very small and it provides larger improvement in lifetime than three other intra-set WLTs and a cache replacement policy.",

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EqualWrites: Reducing Intra-Set Write Variations for Enhancing Lifetime of Non-Volatile Caches

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