응용의 특성을 고려한 NVM 기반 고속 스토리지의 배치 방안

김지선,반효경 한국인터넷방송통신학회 2019 한국인터넷방송통신학회 논문지 Vol.19 No.4

This paper presents an optimized adoption of NVM for the storage system considering application characteristics. To do so, we first characterize the storage access patterns for different application types, and make two prominent observations that can be exploited in allocating NVM storage efficiently. The first observation is that a bulk of I/O does not happen on a single storage partition, but it is varied significantly for different application categories. Our second observation is that there exists a large proportion of single accessing in storage data. Based on these observations, we show that maximizing the storage performance with NVM is not obtained by fixing it as a specific storage partition but by allocating it adaptively for different applications. Specifically, for graph, database, and web applications, using NVM as a swap, a journal, and a file system partitions, respectively, performs well. 본 논문은 응용의 특성을 고려하여 NVM 기반 고속 스토리지를 최적 배치하는 방안을 논의한다. 이를 위해 본논문은 먼저 여러 응용들의 스토리지 접근 특성을 분석하여 효율적인 NVM 배치에 활용가능한 다음의 두 가지 특성을관찰하였다. 그 첫째는 I/O를 집중적으로 발생시키는 스토리지 파티션이 하나로 고정되지 않고 응용에 따라 다르게 나타난다는 점이다. 두 번째는 스토리지 접근에 있어 높은 비율의 1회성 접근 데이터가 존재한다는 점이다. 이와 같은 분석결과를 토대로 본 논문에서는 NVM을 특정 파티션으로 고정 사용하는 것이 아니라 응용의 특성에 맞게 배치하는 것이스토리지 성능을 극대화할 수 있음을 확인하였다. 특히, 그래프, DB, 웹 응용의 경우 NVM을 스왑, 저널, 파일시스템파티션으로 활용하는 것이 효과적임을 확인하였다.

CO2가스를 이용하여 증착된 터널층의 계면포획밀도의 감소와이를 적용한 저전력비휘발성 메모리 특성

이준신,이소진,장경수,Cam Phu Thi Nguyen,김태용 한국전기전자재료학회 2016 전기전자재료학회논문지 Vol.29 No.7

The silicon dioxide (SiO2) was deposited using various gas as oxygen and nitrous oxide (N2O) in nowadays. In order to improve electrical characteristics and the interface state density (Dit) in low temperature, It was deposited with carbon dioxide (CO2) and silane (SiH4) gas by inductively coupled plasma chemical vapor deposition (ICP-CVD). Each Dit of SiO2 using CO2 and N2O gas was 1.30×1010 cm-2·eV-1 and 3.31×1010 cm-2·eV-1. It showed SiO2 using CO2 gas was about 2.55 times better than N2O gas. After 10 years when the thin film was applied to metal/insulator/semiconductor(MIS)-nonvolatile memory(NVM), MIS NVM using SiO2(CO2) on tunneling layer had window memory of 2.16 V with 60% retention at bias voltage from +16 V to -19 V. However, MIS NVM applied SiO2(N2O) to tunneling layer had 2.48 V with 61% retention at bias voltage from +20 V to -24 V. The results show SiO2 using CO2 decrease the Dit and it improves the operating voltage. 실리콘다이옥사이드(silicon dioxide, SiO2)는 산소 또는 N2O가스 같은 다양한 산화성 가스로 증착되었다. 본 실험에서는 저온에서 증착되는 SiO2의 전기적 특성 및 계면포획밀도(interface state density, Dit)를 향상시키기 위해 SiH4과 CO2가스를 사용하여 유도결합플라즈마 화학기상증착(inductively coupled plasma chemical vapor deposition, ICP-VCD)로 SiO2를 증착하였다. CO2와 N2O가스를 이용한 SiO2 박막의 Dit는 각각 1.30 × 1,010 cm-2·eV-1, 3.31 × 1,010 cm-2·eV-1를 보였다. 이는 CO2가스를 사용한 SiO2박막의 Dit가 N2O가스를 이용한 것에 비해 2.55배 낮음을 나타낸다. SiO2(CO2)박막을 터널층을 사용한 금속/절연체/반도체(MIS) 구조의 비휘발성메모리(nonvolatile memory, NVM)는 +16/-19 V의 스트레스전압에서 2.16 V의 윈도우 메모리를 보였지만 SiO2(N2O)박막을 터널층으로 사용한 MIS 구조의 소자는 +20/-24 V의 높은 인가전압에서 2.48 V의 윈도우 메모리를 보였다. 그러므로 SiO2(CO2)박막을 NVM의 터널층으로 사용하면 Dit를 감소시켜 저전압메모리를 구현할 수 있다.

Comparison of Hybrid and Hierarchical Swap Architectures in Android by using NVM

Jisun Kim,Hyokyung Bahn 대한전자공학회 2018 Journal of semiconductor technology and science Vol.18 No.6

As the application ranges supported by smartphones grow rapidly, the necessity of virtual memory swapping is becoming increasingly important. However, current Android platforms do not support swapping because flash memory does not provide consistent performance for swapping. In this paper, we present a novel swap architecture that adds a small size of NVM to efficiently hide the slow swap problem of Android. Specifically, we present an efficient hybrid swap scheme, which prevents the pollution of NVM from a large portion of singleaccess data that we observe in Android swapping traces. Experimental results show that our scheme reduces the number of flash I/Os by 6.2% on average and up to 24% by identifying cold data and prohibiting them from entering NVM. We also show the effectiveness of the proposed scheme under various swap architectures.

Phase Change Memory와 Capacitor-Less DRAM을 사용한 Unified Dual-Gate Phase Change RAM

김주연,Kim, Jooyeon 한국전기전자재료학회 2014 전기전자재료학회논문지 Vol.27 No.2

Dual-gate PCRAM which unify capacitor-less DRAM and NVM using a PCM instead of a typical SONOS flash memory is proposed as 1 transistor. $VO_2$ changes its phase between insulator and metal states by temperature and field. The front-gate and back-gate control NVM and DRAM, respectively. The feasibility of URAM is investigated through simulation using c-interpreter and finite element analysis. Threshold voltage of NVM is 0.5 V that is based on measured results from previous fabricated 1TPCM with $VO_2$. Current sensing margin of DRAM is 3 ${\mu}A$. PCM does not interfere with DRAM in the memory characteristics unlike SONOS NVM. This novel unified dual-gate PCRAM reported in this work has 1 transistor, a low RESET/SET voltage, a fast write/erase time and a small cell so that it could be suitable for future production of URAM.

Characterizing Memory References for Smartphone Applications and Its Implications

Lee, Soyoon,Bahn, Hyokyung The Institute of Electronics and Information Engin 2015 Journal of semiconductor technology and science Vol.15 No.2

As smartphones support a variety of applications and their memory demand keeps increasing, the design of an efficient memory management policy is becoming increasingly important. Meanwhile, as nonvolatile memory (NVM) technologies such as PCM and STT-MRAM have emerged as new memory media of smartphones, characterizing memory references for NVM-based smartphone memory systems is needed. For the deep understanding of memory access features in smartphones, this paper performs comprehensive analysis of memory references for various smartphone applications. We first analyze the temporal locality and frequency of memory reference behaviors to quantify the effects of the two properties with respect to the re-reference likelihood of pages. We also analyze the skewed popularity of memory references and model it as a Zipf-like distribution. We expect that the result of this study will be a good guidance to design an efficient memory management policy for future smartphones.

Characterizing Memory References for Smartphone Applications and Its Implications

Soyoon Lee,Hyokyung Bahn 대한전자공학회 2015 Journal of semiconductor technology and science Vol.15 No.2

As smartphones support a variety of applications and their memory demand keeps increasing, the design of an efficient memory management policy is becoming increasingly important. Meanwhile, as nonvolatile memory (NVM) technologies such as PCM and STT-MRAM have emerged as new memory media of smartphones, characterizing memory references for NVM-based smartphone memory systems is needed. For the deep understanding of memory access features in smartphones, this paper performs comprehensive analysis of memory references for various smartphone applications. We first analyze the temporal locality and frequency of memory reference behaviors to quantify the effects of the two properties with respect to the re-reference likelihood of pages. We also analyze the skewed popularity of memory references and model it as a Zipf-like distribution. We expect that the result of this study will be a good guidance to design an efficient memory management policy for future smartphones.

Characterizing Memory References for Smartphone Applications and Its Implications

이소윤,반효경 대한전자공학회 2015 Journal of semiconductor technology and science Vol.15 No.2

As smartphones support a variety of applications and their memory demand keeps increasing, the design of an efficient memory management policy is becoming increasingly important. Meanwhile, as nonvolatile memory (NVM) technologies such as PCM and STT-MRAM have emerged as new memory media of smartphones, characterizing memory references for NVM-based smartphone memory systems is needed. For the deep understanding of memory access features in smartphones, this paper performs comprehensive analysis of memory references for various smartphone applications. We first analyze the temporal locality and frequency of memory reference behaviors to quantify the effects of the two properties with respect to the re-reference likelihood of pages. We also analyze the skewed popularity of memory references and model it as a Zipf-like distribution. We expect that the result of this study will be a good guidance to design an efficient memory management policy for future smartphones.

향상된 NVM에 대한 가격과 IOPS간 트레이드오프 분석

안제민(Jemin Ahn),강경태(Kyungtae Kang) 한국컴퓨터정보학회 2017 한국컴퓨터정보학회 학술발표논문집 Vol.25 No.2

스왑 지원 스마트폰의 메모리 쓰레싱 분석 및 관리 방안

반효경,김지선 한국인터넷방송통신학회 2023 한국인터넷방송통신학회 논문지 Vol.23 No.2

As the use of smartphones expands to various areas and the level of multitasking increases, the support of swap is becoming increasingly important. However, swap support in smartphones is known to cause excessive storage traffic, resulting in memory thrashing. In this paper, we analyze how the thrashing of swaps that occurred in early smartphones has changed with the advancement of smartphone hardware. As a result of this analysis, we show that the swap thrashing problem can be resolved to some extent when the memory size increases. However, we also show that thrashing still occurs when the number of running apps continues to increase. Based on further analysis, we observe that this thrashing is caused by some hot data and suggest a way to solve this through an NVM-based architecture. Specifically, we show that a small size NVM with judicious management can resolve the performance degradation caused by smartphone swap.

ONO 구조의 nc-si NVM의 전기적 특성

백경현,정성욱,장경수,유경열,안시현,이준신 한국진공학회 2011 한국진공학회 학술발표회초록집 Vol.40 No.0