Analysis of Memory Ballooning Technique for Dynamic Memory Management of Virtual Machines (VMs)

A. B. M. Moniruzzaman 보안공학연구지원센터 2014 International Journal of Grid and Distributed Comp Vol.7 No.6

Memory ballooning is dynamic memory management technique for virtual machines (VMs). Ballooning is a part of memory reclamation technique operations used by a hypervisor to allow the physical host system to retrieve unused memory from certain guest virtual machines (VMs) and share it with others. Memory ballooning allows the total amount of RAM required by guest VMs to exceed the amount of physical RAM available on the host. Memory overcommitment enables a higher consolidation ratio in a hypervisor. Using memory overcommitment, users can consolidate VMs on a physical machine such that physical resources are utilized in an optimal manner while delivering good performance. Hence memory reclamation is an integral component of memory overcommitment. In this paper, we address that the basic cause of memory that ballooning is memory overcommitment from using memory-intensive virtual machines. We compared to others reclamation technique and identify Cost Associate with Memory Ballooning in state of Memory Overcommitment. The objective of this paper is to analyse memory ballooning technique for dynamic memory management of VMs. For this analysis, VMware based virtualization software, e.g., ESXi Server, vCenter Server, vSphere Client are installed and configured on the Centre for Innovation and Technology (CIT) Lab, DIU; for monitor and analyze VM performance for memory ballooning technique. The performance of memory ballooning technique is evaluated with two different test cases. The purpose is to help users understand, how this technique impact the performance. Finally, we presents the throughput of heavy workload with different memory limits when using ballooning or swapping; and analyse VM performance issue for this technique.

Flash Memory Pattern Test를 위한 효율적인 알고리즘 연구

김태환,장훈 한국차세대컴퓨팅학회 2016 한국차세대컴퓨팅학회 논문지 Vol.12 No.6

스마트폰, 태블릿 PC, 울트라북등 휴대기기 사용의 증가로 인해 NAND-형 Flash Memory의 수요도 지속적으로 증가하고 있다. 그렇기 때문에 NAND-형 Flash Memory에서 발생할 수 있는 고장을 진단하기 위한 알고리즘 연 구가 매우 중요하다. Flash Memory는 셀 배열구조에 따라서 NOR-형 Flash Memory와 NAND-형 Flash Memory로 구분이 된다. NOR-형 Flash Memory는 다양한 테스트 알고리즘과 BIRA(Built-in Redundancy Analysis)알고리즘, 진단 알고리즘 등 다양한 알고리즘 연구가 진행되어 왔다. 그러나 NOR-형 Flash Memory에 서 연구되었던 이러한 알고리즘들을 이용하여 NAND-형 Flash Memory를 위한 고장을 확인하는 것이 매우 어렵 다. 따라서 본 논문에서는 NAND-형 Flash Memory에서 발생할 수 있는 고장 확인이 가능한 정확하고 효율적인 진단 알고리즘을 제안한다. 그래서 NAND-형 Flash Memory를 위한 고장 진단을 가능하게 한다. The increasing usage of mobile devices such as SmartPhone, TabletPC, and Ultrabook, the demand for NAND-type Flash Memory is also constantly growing. Therefore, high speed and miniaturization able, NAND-type Flash Memory’s research for diagnosis of possible malfunction is very important. The Flash Memory is divided into NOR-type Flash Memory, and NAND-type Flash Memory. A lot of study such as Test Algorithm, BISR(Built-In Self Repair) Algorithm and Diagnostic Algorithm, etc. has been progressed in NOR-type Flash Memory. However, it is very difficult to detect for NAND-type Flash Memory’s fault, with the former studies of algorithms for NOR-type Flash Memory. In this paper, an efficient and accurate problem diagnosable algorithm that can identify, the type of possible failure of the cell in NAND-type Flash Memory, is proposed. So it allows error diagnosing for NAND-type Flash Memory.

Hybrid in-memory storage for cloud infrastructure

( Dae Won Kim ),( Sun Wook Kim ),( Soo Cheol Oh ) 한국인터넷정보학회 2021 인터넷정보학회논문지 Vol.22 No.5

Modern cloud computing is rapidly changing from traditional hypervisor-based virtual machines to container-based cloud-native environments. Due to limitations in I/O performance required for both virtual machines and containers, the use of high-speed storage (SSD, NVMe, etc.) is increasing, and in-memory computing using main memory is also emerging. Running a virtual environment on main memory gives better performance compared to other storage arrays. However, RAM used as main memory is expensive and due to its volatile characteristics, data is lost when the system goes down. Therefore, additional work is required to run the virtual environment in main memory. In this paper, we propose a hybrid in-memory storage that combines a block storage such as a high-speed SSD with main memory to safely operate virtual machines and containers on main memory. In addition, the proposed storage showed 6 times faster write speed and 42 times faster read operation compared to regular disks for virtual machines, and showed the average 12% improvement of container’s performance tests.

NAND Flash Memory Pattern Test를 위한 PMBIST

김태환(Tae-Hwan Kim),장훈(Hoon Chang) 대한전자공학회 2014 전자공학회논문지 Vol.51 No.1

최근 새롭게 보급되는 휴대기기(스마트폰, 울트라북, 태블릿 PC)로 인하여 고용량과 빠른 속도를 원하는 소비자가 증가하고 있다. 이에 따라 Flash Memory의 수요도 지속적으로 증가하고 있다. Flash Memory는 NAND형과 NOR형으로 구분되어 있다. NAND형 Flash Memory는 NOR형 Flash Memory에 비해 속도는 느리지만 가격이 저렴하다. 그렇기 때문에 NAND형 Flash Memory는 Mobile 시장에서 많이 사용되어지고 있다. 그래서 Flash Memory Test를 위한 Fault 검출은 메우 중요하다. 본 논문에서는 Fault 검출 향상을 위한 NAND형 Flash Memory의 Pattern Test를 위한 PMBIST를 제안한다. It has been an increase in consumers who want a high-capacity and fast speed by the newly diffused mobile device(Smart phones, Ultra books, Tablet PC). As a result, the demand for Flash Memory is constantly increasing. Flash Memory is separated by a NAND-type and NOR-type. NAND-type Flash Memory speed is slow, but price is cheaper than the NOR-type Flash Memory. For this reason, NAND-type Flash Memory is widely used in the mobile market. So Fault Detection is very important for Flash Memory Test. In this paper, Proposed PMBIST for Pattern Test of NAND-type Flash Memory improved Fault detection.

메모리가 적은 자바 시스템을 위한 자동 동적 메모리 관리 기법 (pp.378-384)

최형규(Hyung-Kyu Choi),문수묵(Soo-Mook Moon) 한국정보과학회 2008 정보과학회논문지 : 시스템 및 이론 Vol.35 No.7·8

많은 내장형 시스템들이 자바(Java)를 널리 채택하고 있다. 내장형 시스템은 자바 가상 머신을 통해 자바를 지원하며, 자바 가상 머신은 쓰레기 수집기(Garbage Collector)를 통해서 동적 메모리를 자동으로 관리한다. 내장형 시스템은 적은 메모리를 가지고 있기 때문에 자바 가상 머신은 이를 효율적으로 관리해야 한다. 본 논문에서는 여러 자바 프로그램을 동시에 실행할 수 있는 자바 가상 머신에서 적은 메모리를 사용하면서도 효과적으로 메모리를 관리할 수 있는 메모리 관리 기법을 제안한다. 우선 개선된 압축(compaction)기법 기반의 쓰레기 수집 기법을 소개하여 움직일 수 없는 메모리 영역이 존재하더라도 외부 단편화(external fragmentation) 문제를 극복한다. 다음으로 수행 중 메모리 사용을 줄이기 위해서 쓰레기 수집기가 메모리에서 필요 없는 클래스(class)들을 선택적으로 수거하는 class unloading 기법을 소개한다. 소개한 기법들을 실제 동작하는 내장형 시스템에서 실험한 결과, 메모리가 부족하여 동시에 수행할 수 없었던 프로그램들이 같이 수행되는 등 매우 효과적이었다. Many embedded systems are supporting Java as their software platform via Java virtual machine. Java virtual machine manages memory automatically by providing automatic memory management, i.e. garbage collector. Because only scarce memory is available to embedded system, Java virtual machine should use small memory and manage it efficiently. This paper introduces two memory management techniques to exploit small memory in Java virtual machine which can execute multiple Java applications concurrently. First, compaction based garbage collection is introduced to overcome external fragmentation problem in presence of immovable memory area. Then garbage collector driven class unloading is introduced to reduce memory use of unnecessary loaded classes. We implemented these techniques in working embedded system and observed that they are very efficient, since more Java applications are able to be executed concurrently and memory use is also reduced with these techniques.

Design and implementation of content based page sharing method in Xen for the International Conference on Control, Automation and Systems 2008 (ICCAS 2008)

Mikinori Eto,Hidenori Umeno 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10

Modern computers are not only sufficiently powerful but also inexpensive. However there are few opportunities for application programs to use its capabilities. On the other hand, the number of computers has been increasing in the business sectors and other fields. Thus there are a lot of needless modern computer utilizations. As these solutions, researchers interested with the utilization of virtual machines (VMs) have been rising. The VM system enables consolidation of several real machines. As we consolidate real machine, another problem occurs. It may run several the same operating systems (OSs) which have identical application program, component and data on a machine. In this case, real machine’ memory has same contents. If many machines are consolidated by VM, it is verbose. We have been developing original VM system based on open source and high-quality VM system Xen. In this paper, we improved memory management system of Xen and consider the method for decreasing verbose memory on real machine. We propose the design and implementation method of content based page sharing method in Xen.

언어학과 기계 번역-한문학 텍스트의 기계 번역과 관련하여

정성훈 근역한문학회 2019 한문학논집(漢文學論集) Vol.53 No.-

This study examines the history of machine translation in relation to linguistics and briefly introduces algorithms for rule based machine translation and data based machine translation. And the purpose of this study is to propose and prospect a machine translation of Korean texts in classical Chinese. Machine translation is a technology that automatically transforms a language into another language. Recently, it has been actively researched in artificial intelligence(AI) and computational linguistics. Machine translation started with Weaver(1949), and until the early 1980’s, rule based machine translation developed which is a system that applied many rules for vocabulary, grammar, and meaning. Since the 1980’s, the attempts using corpus for machine translation come up with computer development and large corpus construction, then data base machine translation has developed. In recent years, the machine translations with AI has become very popular. One of them is ‘Neural Machine Translation’. However, it is difficult to use rule based machine translation because it is not the agreed-on situation about vocabulary and grammar on Korean literature text in classical Chinese. Also, since there are not enough parallel corpora, it is difficult to use statistical machine translation or neural machine translation. Therefore, the most reasonable method of machine translation on Korean literature text in classical Chinese is to use ‘translation memory’. It is possible to minimize the time and cost for translating the current Korean literature text in classical Chinese, and to generate a large amount of parallel corpus which is required in neural network machine translation in the future. 본 연구는 언어학과 관련하여 기계 번역의 역사를 살펴보고, 규칙 기반 기계 번역과 자료 기반 기계 번역의 알고리듬을 간략히 소개한다. 또한 이를 통해 한문학 텍스트의 기계 번역에 대한 제안과 전망을 하는 것이 본 연구의 목적이다. 기계 번역은 컴퓨터를 이용하여 하나의 언어를 다른 언어로 자동으로 변환하는 기술인데, 최근 인공 지능(AI)과 전산언어학 분야에서 활발히 연구되고 있다. 기계 번역은 Weaver(1949)에서 출발하였으며, 1980년대 초까지 언어학의 영향으로 어휘, 문법, 의미 생성에 필요한 많은 규칙을 적용한 시스템인 규칙 기반 기계 번역이 발전하였다. 1980년대 이후에는 컴퓨터의 발달과 대규모 코퍼스(corpus)의 구축이 가능해지면서 코퍼스를 기계 번역에 이용하려는 시도들이 나타났는데, 코퍼스를 기반으로 하는 자료 기반 기계 번역이 발전하였다. 최근에는 딥러닝(deep learning)을 통한 기계 번역의 인기가 매우 높아지고 있다. 그 중 주목받고 있는 기술은 ‘신경망 기계 번역(Neural Machine Translation)’이다. 그런데 한문학 텍스트는 어휘와 문법에 대한 정확한 정의와 분류가 합의된 상황도 아닐 뿐만 아니라 이를 규칙화한 시스템도 구축하지 못한 상황이기 때문에 규칙 기반 기계 번역을 활용하기 어렵다. 한편 충분한 병렬 코퍼스도 부족하기 때문에 통계적 기계 번역이나 신경망 기계 번역을 활용하기도 어렵다. 따라서 현재 한문학 텍스트의 기계 번역에서 가장 합리적인 방법은 번역 메모리를 활용하는 방법이다. 이를 통해 현재 한문학 텍스트의 번역에 대한 시간과 비용을 최소화 할 수 있고, 향후 신경망 기계 번역에서 필요로 하는 대용량의 병렬 코퍼스를 생성해 낼 수 있을 것이다.

A Study on Efficient Memory Management Using Machine Learning Algorithm

Beom-Joo Park,Min-Soo Kang,Minho Lee,Yong Gyu Jung 한국인터넷방송통신학회 2017 Journal of Advanced Smart Convergence Vol.6 No.1

As the industry grows, the amount of data grows exponentially, and data analysis using these serves as a predictable solution. As data size increases and processing speed increases, it has begun to be applied to new fields by combining artificial intelligence technology as well as simple big data analysis. In this paper, we propose a method to quickly apply a machine learning based algorithm through efficient resource allocation. The proposed algorithm allocates memory for each attribute. Learning Distinct of Attribute and allocating the right memory. In order to compare the performance of the proposed algorithm, we compared it with the existing K-means algorithm. As a result of measuring the execution time, the speed was improved.

메모리가 제한적인 자바가상기계에서의 지역 재사용

김태인(Taein Kim),김성건(Seonggun Kim),한환수(Hwansoo Han) 한국정보과학회 2007 정보과학회논문지 : 소프트웨어 및 응용 Vol.34 No.6

많은 연구들을 통해 수행 속력, 효율성, 용이성, 안전성을 위하여 메모리 관리 기법들을 개선시켰다. 그러한 방법들 중에서 지역별 메모리 관리 기법은 각각의 객체 할당 위치에서 따라 정해진 지역에 할당 시키고 그 지역이 제거된다면 그 곳에 할당된 모든 객체의 메모리를 반환하는 방법이다. 본 논문에서는 메모리 제약적인 환경에서 힙 메모리 사용량을 줄이기 위해 로컬 지역을 재사용하는 방법을 제시한다. 기본 아이디어는 현재 함수가 수행될 동안 사용하지 않는 상위 로컬 지역을 재사용하는 것이다. 이러한 방법을 사용함으로써 메모리 제약적인 환경에서 메모리의 한계를 극복할 수 있을 것이다. Various researches had been devoted in purpose of improving memory management in terms of performance, efficiency, ease of use, and safety. One of these approaches is a region-based memory management. Each allocation site selects a specific region, after that allocated objects are placed in this region. Memory is reclaimed by destroying the region, freeing all the objects allocated therein. In this paper, we propose reusing of local regions to reduce heap memory usage in memory-limited environments. The basic idea of this proposal is reusing of upper local regions where objects that are allocated to these regions are not accessed until the current method is finished. We believe our method of reusing local regions is able to overcome memory constraints in memory-limited environments.

Chilled Air System and Size Effect in Micro-milling of Nickel-Titanium Shape Memory Alloys

Zailani Zainal Abidin,Paul Tarisai Mativenga,Gary Harrison 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.7 No.2

Although Nickel-Titanium Shape Memory Alloys (NiTi SMAs) are used in a variety of applications due to their shape memory and superelasticity properties, their features of high ductility, temperature sensitivity, and strong work hardening render these materials difficult to machine. The viability of a new approach in improving the machinability through temperature control using chilled air system application was investigated. Differential scanning calorimetry was used to characterise material response to thermal loads. Microstructure phase identification was evaluated with X-ray diffraction. Micro-milling tests were performed using chilled air system and benchmarked to dry cutting and the use of minimum quantity lubricant (MQL). To augment lubrication, chilled air was also applied concurrently with MQL. Results indicated that the application of chilled air reduced cutting temperature and minimised burr height, while their simultaneous application with MQL further improved the machinability. Further investigation was conducted to explore the influence of the ploughing mechanism on machining performance and product quality. The results pointed to higher feed per tooth producing better outcomes. This paper puts forward a new hypothesis that the machinability could be improved by inhibiting or locking in phase transformation through temperature control, and optimising chip thickness, one of the principal parameters of size effect.