Integration of Retention-aware Refresh and BISR Techniques for DRAM Refresh Power Reduction

Cheng, Wei-Chen; Chen, Jian-Kai; Huang, Shih-Hsu

doi:10.1109/isocc.2018.8649914

Cited by 1 publication

(4 citation statements)

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“…For the RAAR technique proposed by research [4], only refresh bundles that contain weak rows need a refresh in each refresh interval. However, weak rows distribution between refresh bundles may differ dramatically.…”

Section: Motivation and Examplementioning

confidence: 99%

“…There has been some research on reducing the overhead of DRAM by retention-aware refresh or refresh scheduling [3,4,5,6,7,8,9,10,11,12]. Research [4] proposed a RAAR technique to reduce refresh energy and performance degradation, only part of refresh bundles need a refresh in each refresh interval, while other refresh bundles can skip at least 50% of refresh operations. Although this methodology could reduce a lot of redundant refreshes, because it chose a unique refresh scheme all over the RAAR period, it still wastes quite a number of refresh time on normal cells.…”

Section: Introductionmentioning

confidence: 99%

“…As observed in research [7], a refreshing bundle that contains weak rows still contain lots of normal cells even if we choose the optimal refresh scheme for it. Therefore, research [8] proposed an integration scheme to integrate RAAR and built-in self-repair (BISR) technique, selected weak rows are repaired with the BISR technique to minimize refresh overhead of refresh bundles.…”

Section: Introductionmentioning

confidence: 99%

“…In summary of the related works that addressed the RAAR technique, although research [5] had proposed an integration refresh scheme, it did not integrate the 2x granularity auto-refresh and hence the performance improvement was less than 10%. Research [6] and research [8] also reveal the fact that although they integrated RAAR scheme with bank ordering and BISR technique, respectively, there was still very little performance improvement achieved. All these were because that weak cells only occupy a low percentage of all memory cells, if the 2x granularity was not integrated into the refresh scheme, all other optimization techniques can only obtain limited reduction on refresh overhead.…”

Section: Introductionmentioning

confidence: 99%

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Retention-Aware DRAM Auto-Refresh Scheme for Energy and Performance Efficiency

Cheng

Shen

2019

Micromachines

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Dynamic random access memory (DRAM) circuits require periodic refresh operations to prevent data loss. As DRAM density increases, DRAM refresh overhead is even worse due to the increase of the refresh cycle time. However, because of few the cells in memory that have lower retention time, DRAM has to raise the refresh frequency to keep the data integrity, and hence produce unnecessary refreshes for the other normal cells, which results in a large refresh energy and performance delay of memory access. In this paper, we propose an integration scheme for DRAM refresh based on the retention-aware auto-refresh (RAAR) method and 2x granularity auto-refresh simultaneously. We also explain the corresponding modification need on memory controllers to support the proposed integration refresh scheme. With the given profile of weak cells distribution in memory banks, our integration scheme can choose the most appropriate refresh technique in each refresh time. Experimental results on different refresh cycle times show that the retention-aware refresh scheme can properly improve the system performance and have a great reduction in refresh energy. Especially when the number of weak cells increased due to the thermal effect of 3D-stacked architecture, our methodology still keeps the same performance and energy efficiency.

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Section: Motivation and Examplementioning

confidence: 99%