DRAM refresh improvement with bank reordering

Cheng, Wei-Chen; Li, Xin-Lun; Chen, Jian-Kai

doi:10.1109/isne.2018.8394713

Cited by 2 publications

(3 citation statements)

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“…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.…”

Section: Introductionmentioning

confidence: 99%

“…Research [5] improved this phenomenon by integrating all the RAAR refresh schemes and chose the optimal refresh scheme for different refresh bundles to minimize refresh time and refresh energy. Research [6] integrated the RAAR scheme with the bank reordering technique to gather up weak rows in adjacent banks, and hence less refresh bundles need refresh in each refresh interval. 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.…”

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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