• Title/Summary/Keyword: non volatile memory

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Tracking Cold Blocks for Static Wear Leveling in FTL-based NAND Flash Memory (메모리에서 정적 마모도 평준화를 위한 콜드 블록 추적 기법)

  • Jang, Yonghun;Kim, Sungho;Hwang, Sang-Ho;Lee, Myungsub;Park, Chang-Hyeon
    • IEMEK Journal of Embedded Systems and Applications
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    • v.12 no.3
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    • pp.185-192
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    • 2017

  • Due to the characteristics of low power, high durability and high density, NAND flash memory is being heavily used in various type of devices such as USB, SD card, smart phone and SSD. On the other hand, because of another characteristic of flash cell with the limited number of program/erase cycles, NAND flash memory has a short lifetime compared to other storage devices. To overcome the lifetime problem, many researches related to the wear leveling have been conducted. This paper presents a method called a TCB (Tracking Cold Blocks) using more reinforced constraint conditions when classifying cold blocks than previous works. TCB presented in this paper keeps a MCT (Migrated Cold block Table) to manage the enhanced classification process of cold blocks, with which unnecessary migrations of pages can be reduced much more. Through the experiments, we show that TCB reduces the overhead of wear leveling by about 30% and increases the lifetime up to about 60% compared to BET and BST.

  • https://doi.org/10.14372/IEMEK.2017.12.3.185 인용 PDF KSCI

Recency and Frequency based Page Management on Hybrid Main Memory

  • Kim, Sungho;Kwak, Jong Wook
    • Journal of the Korea Society of Computer and Information
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    • v.23 no.3
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    • pp.1-8
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    • 2018

  • In this paper, we propose a new page replacement policy using recency and frequency on hybrid main memory. The proposal has two features. First, when a page fault occurs in the main memory, the proposal allocates it to DRAM, regardless of operation types such as read or write. The page allocated by the page fault is likely to be high probability of re-reference in the near future. Our allocation can reduce the frequency of write operations in PCM. Second, if the write operations are frequently performed on pages of PCM, the pages are migrated from PCM to DRAM. Otherwise, the pages are maintained in PCM, to reduce the number of unnecessary page migrations from PCM. In our experiments, the proposal reduced the number of page migrations from PCM about 32.12% on average and reduced the number of write operations in PCM about 44.64% on average, compared to CLOCK-DWF. Moreover, the proposal reduced the energy consumption about 15.61%, and 3.04%, compared to other page replacement policies.

  • https://doi.org/10.9708/jksci.2018.23.03.001 인용 PDF KSCI

Dynamic Data Migration in Hybrid Main Memories for In-Memory Big Data Storage

  • Mai, Hai Thanh;Park, Kyoung Hyun;Lee, Hun Soon;Kim, Chang Soo;Lee, Miyoung;Hur, Sung Jin
    • ETRI Journal
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    • v.36 no.6
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    • pp.988-998
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    • 2014

  • For memory-based big data storage, using hybrid memories consisting of both dynamic random-access memory (DRAM) and non-volatile random-access memories (NVRAMs) is a promising approach. DRAM supports low access time but consumes much energy, whereas NVRAMs have high access time but do not need energy to retain data. In this paper, we propose a new data migration method that can dynamically move data pages into the most appropriate memories to exploit their strengths and alleviate their weaknesses. We predict the access frequency values of the data pages and then measure comprehensively the gains and costs of each placement choice based on these predicted values. Next, we compute the potential benefits of all choices for each candidate page to make page migration decisions. Extensive experiments show that our method improves over the existing ones the access response time by as much as a factor of four, with similar rates of energy consumption.

  • https://doi.org/10.4218/etrij.14.0114.0012 인용 PDF KSCI KPUBS

Design of RE Passive Smart Card for the Subway Ticket

  • Yang, Kyeong-Rok;Jin, In-Su;Ryu, Hyoung-sun;Kim, Yang-mo
    • Proceedings of the IEEK Conference
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    • 2000.07b
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    • pp.583-586
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    • 2000

  • A passive RF smart card incorporating a non volatile memory element is powered by inductive coupling to a proximately located RF reader. Therefore, the power consumption in the smart card should be low. In this study, we designed the low power passive RF smart card that is operated at 125kHz to apply to the subway ticket system.

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