• Title, Summary, Keyword: NVRAM

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Design and Implementation of a File System that Considers the Space Efficiency of NVRAM (비휘발성 메모리의 공간적 효율성을 고려한 파일 시스템의 설계 및 구현)

  • Hyun Choul-Seung;Baek Seung-Jae;Choi Jong-Moo;Lee Dong-Hee;Noh Sam-H.
    • Journal of KIISE:Computer Systems and Theory
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    • v.33 no.9
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    • pp.615-625
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    • 2006
  • Nonvolatile memory technology is evolving continuously and commercial products such as FeRAM and PRAM are now challenging their markets. As NVRAM has properties of both memory and storage, it can store persistent data objects while allowing fast and random access. To utilize NVRAM for general purpose storing of frequently updated data across power disruptions, some essential features of the file system including naming, recovery, and space management are required while exploiting memory-like properties of NVRAM. Conventional file systems, including even recently developed NVRAM file systems, show very low space efficiency wasting more than 50% of the total space in some cases. To efficiently utilize the relatively expensive NVRAM, we design and implement a new extent-based space-thrifty file system, which we call NEBFS (NVRAM Extent-Based File System). We analyze and compare the space utilization of conventional file systems with NEBFS and validate the results with experimental results observed from running the file system implementations on a system with actual NVRAM installed as well as on systems emulating NVRAM. We show that NEBFS has high space efficiency compared to conventional file systems.

Design of memory controller for Non-volatile main memory (NVRAM 주 메모리를 위한 메모리 컨트롤러 설계)

  • Lee, Hu-Ung;Won, Youjip
    • Proceedings of the Korean Society of Computer Information Conference
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    • pp.195-196
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    • 2013
  • 본 논문에서는 NVRAM(Non-volatile Random Access Memory) 주 기억장치를 위한 메모리 컨트롤러를 설계한다. NVRAM의 비 휘발성과 낮은 정적 에너지 소모의 장점을 활용하는 한편, 상대적으로 느린 읽기/쓰기 속도 및 큰 쓰기 전력 소모를 개선하기 위해 새로운 캐시 구조를 제안한다. FPGA를 활용하여 Block RAM 128KB 1차 캐시, 16KB 2차 캐시 및 캐시 컨트롤러를 포함하는 메모리 컨트롤러를 구현하였고 NVRAM은 FeRAM를 사용하였다.

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Reducing the User-perceived Latency of Browsers with NVRAM

  • Kim, Kyusik;Cho, Yongwoon;Kim, Seongmin;Kim, Taeseok
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.17 no.1
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    • pp.23-28
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    • 2017
  • Non-volatile RAM (NVRAM) provides many opportunities to improve the performance of computing devices. In this paper, we present an approach that reduces the user-perceived latency of browsers by using NVRAM. To this end, we first analyze the browser launch process, and then employ several techniques that improve the performance of each step by using NVRAM. Specially, we focus on minimizing the launch time of browser by 1) prefetching the block sequence required for browser launch, 2) caching the web resources in the fast NVRAM, and 3) reusing the displayed bitmap data in the frame buffer. Through implementation, we show that our scheme significantly reduces the launch time of browsers.

A Page Placement Scheme of Smartphone Memory with Hybrid Memory (이기종 메모리로 구성된 스마트폰 메모리의 페이지 배치 기법)

  • Lee, Soyoon;Bahn, Hyokyung
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.20 no.1
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    • pp.149-153
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    • 2020
  • This paper presents a new page placement policy for DRAM/NVRAM hybrid main memory in smartphones. Unlike previous studies on hybrid memory systems, this paper performs the placement of pages based on the offline analysis of memory access behaviors as smartphone's memory accesses are skewed to a certain address ranges, which is consistent regardless of smartphone applications, specially for write operations. Thus, we aim at reducing the write traffic to NVRAM by the offline analysis results. Experimental results show that the proposed policy reduces the write traffic to NVRAM by 61% on average without performance degradations.

Scaling down data/index page structure of the NVRAM based DBMS with the small size blocks (소형 블록 DBMS의 데이터/인덱스 페이지 구조 소형화를 통한 NVRAM 성능 개선)

  • Bae, Sang-Hee;Lee, Taehwa;Cha, Jaehyuk
    • Journal of Digital Contents Society
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    • v.14 no.1
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    • pp.15-23
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    • 2013
  • In response to the demands of large-scale data processing with low-power and new application, a storage system using SSD (Solid State Disk/Drive) with fast input-output performance instead of hard disc has appeared as storage device. Studies on methods to overcome specific problems of SSD such as various processing data units, out-place-update and limited delete count have been actively conducted. However, declining performance and stability have not been resolved yet when storing case specific data with small scale that causes frequent random write in hard disc or SSD. This thesis suggests a system structure that stores index requesting frequent random write in NVRAM capable of byte access by using characteristics such as byte unit fast read / write of NVRAM, non-volatile and smaller size of actual changed data size in index page than block size.

DJFS: Providing Highly Reliable and High-Performance File System with Small-Sized NVRAM

  • Kim, Junghoon;Lee, Minho;Song, Yongju;Eom, Young Ik
    • ETRI Journal
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    • v.39 no.6
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    • pp.820-831
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    • 2017
  • File systems and applications try to implement their own update protocols to guarantee data consistency, which is one of the most crucial aspects of computing systems. However, we found that the storage devices are substantially under-utilized when preserving data consistency because they generate massive storage write traffic with many disk cache flush operations and force-unit-access (FUA) commands. In this paper, we present DJFS (Delta-Journaling File System) that provides both a high level of performance and data consistency for different applications. We made three technical contributions to achieve our goal. First, to remove all storage accesses with disk cache flush operations and FUA commands, DJFS uses small-sized NVRAM for a file system journal. Second, to reduce the access latency and space requirements of NVRAM, DJFS attempts to journal compress the differences in the modified blocks. Finally, to relieve explicit checkpointing overhead, DJFS aggressively reflects the checkpoint transactions to file system area in the unit of the specified region. Our evaluation on TPC-C SQLite benchmark shows that, using our novel optimization schemes, DJFS outperforms Ext4 by up to 64.2 times with only 128 MB of NVRAM.

A Status Report on the Implementation of a Flash File System that Exploits Non-Volatile RAM (차세대 비휘발성 메모리를 활용한 플래시 파일 시스템 연구)

  • Park Se Eun;Choi Jongmoo;Lee Donghee;Noh Sam H.
    • Proceedings of the Korean Information Science Society Conference
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    • pp.844-846
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    • 2005
  • 차세대 비휘발성 메모리(Non-Volatile RAM, 이후 NVRAM)의 사용이 현실화 되면서 이를 활용한 저장 장치의 성능 개선 연구가 활발히 진행되고 있다. 본 논문에서는 NVRAM을 이용한 플래시 파일 시스템의 성능 향상 방법을 제안한다. 우선 자주 갱신 되는 정보를 NVRAM에 유지시켜 플래시 메모리의 덮어쓰기(overwrite)로 인한 성능 저하 문제를 개선한다. 또한 NVRAM에 파일시스템의 메타 정보 위치를 유지하여 파일 시스템을 마운트할 때 요구되는 플래시 메모리의 탐색 공간을 줄인다. 실험 결과 마운팅 시간이 줄고 플래시 메모리의 접근 횟수가 감소함을 확인하였다.

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Consideration on Using NVRAM as Index Storage (인덱스 저장을 위한 NVRAM 활용 방안)

  • Joo, Won-Jin;Jung, Ho-Young;Cha, Jae-Hyuk
    • Proceedings of the Korea Information Processing Society Conference
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    • pp.1777-1779
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    • 2010
  • 최근 저전력과 새로운 응용의 대용량 데이터 처리 요구에 따라 저장 장치로 하드디스크 대신 빠른 입출력 성능을 가진 SSD 를 저장장치로 활용하는 사례가 증가하고 있으나 빈번한 임의 쓰기를 발생하는 소규모 특정 데이터를 하드디스크나 SSD 에 저장하는 경우 발생하는 성능 및 안정성 저하문제는 아직 완전히 해결하지 못하고 있다. 본 논문에서는 빈번한 임의 쓰기를 요구하는 인덱스를 바이트 접근이 가능한 NVRAM 에 저장하는 시스템 구조를 제안한다. 제안하는 시스템 구조는 NVRAM 의 바이트 단위 빠른 읽기/쓰기와 인덱스 페이지 내 실제 데이터 변경 크기가 블록 크기보다 훨씬 작다는 특성을 고려하여 인덱스 페이지 크기를 최적화하고 메인 메모리에서 인덱스 페이지 버퍼를 따로 할당하여 관리함으로써 시스템 성능 향상을 기대할 수 있음을 보인다.

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Energy-Efficient Storage with Flash Device in Wireless Sensor Networks (무선 센서 네트워크에서 플래시 장치를 활용한 에너지 효율적 저장)

  • Park, Jung Kyu;Kim, Jaeho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.42 no.5
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    • pp.975-981
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    • 2017
  • In this paper, we propose a method for efficient use of energy when using flash device in WSN environment. Typical Flash devices have a drawback to be an energy efficient storage media in the energy-constrained WSNs due to the high standby energy. An energy efficient approach to deploy Flash devices into WSNs is simply turning the Flash device off whenever idle. In this regard, we make the simple but ideal approach realistic by removing these two obstacles by exploiting nonvolatile RAM (NVRAM), which is an emerging memory technology that provides both non-volatility and byte-addressability. Specifically, we make use of NVRAM as an extension of metadata storage to remove the FTL metadata scanning process that mainly incurs the two obstacles. Through the implementation and evaluation in a real system environment, we verify that significant energy savings without sacrificing I/O performance are feasible in WSNs by turning off the Flash device exploiting NVRAM whenever it becomes idle. Experimental results show that the proposed method consumes only about 1.087% energy compared to the conventional storage device.

Design and Implementation of the Flash File System that Maintains Metadata in Non-Volatile RAM (메타데이타를 비휘발성 램에 유지하는 플래시 파일시스템의 설계 및 구현)

  • Doh, In-Hwan;Choi, Jong-Moo;Lee, Dong-Hee;Noh, Sam-H.
    • Journal of KIISE:Computer Systems and Theory
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    • v.35 no.2
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    • pp.94-101
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    • 2008
  • Non-volatile RAM (NVRAM) is a form of next-generation memory that has both characteristics of nonvolatility and byte addressability each of which can be found in nonvolatile storage and RAM, respectively. The advent of NVRAM may possibly bring about drastic changes to the system software landscape. When NVRAM is efficiently exploited in the system software layer, we expect that the system performance can be significantly improved. In this regards, we attempt to develop a new Flash file system, named MiNVFS (Metadata in NVram File System). MiNVFS maintains all the metadata in NVRAM, while storing all file data in Flash memory. In this paper, we present quantitative experimental results that show how much performance gains can be possible by exploiting NVRAM. Compared to YAFFS, a typical Flash file system, we show that MiNVFS requires only minimal time for mounting. MiNVFS outperforms YAFFS by an average of around 400% in terms of the total execution time for the realistic workloads that we considered.