• Title, Summary, Keyword: Virtual Memory System

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Design of Virtual Memory Compression System on the Embedded System (임베디드 시스템에서 가상 메모리 압축 시스템 설계)

  • Jeong, Jin-Woo;Jang, Seung-Ju
    • The KIPS Transactions:PartA
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    • v.9A no.4
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    • pp.405-412
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    • 2002
  • The embedded system has less fast CPU and lower memory than PC(personal Computer) or Workstation system. Therefore embedded operating is system is designed to efficiently use the limited resource in the system. Virtual memory management or the embedded linux have a low efficiency when page fault is occurred to get a data from I/O device. Because a data is moving from the swap device to main memory. This paper suggests virtual memory compression algorithm for improving in virtual memory management and capacity of space. In this paper, we present a way to performance implement a virtual memory compression system that achieves significant improvement for the embedded system.

A Memory Configuration Method for Virtual Machine Based on User Preference in Distributed Cloud

  • Liu, Shukun;Jia, Weijia;Pan, Xianmin
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.12 no.11
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    • pp.5234-5251
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    • 2018
  • It is well-known that virtualization technology can bring many benefits not only to users but also to service providers. From the view of system security and resource utility, higher resource sharing degree and higher system reliability can be obtained by the introduction of virtualization technology in distributed cloud. The small size time-sharing multiplexing technology which is based on virtual machine in distributed cloud platform can enhance the resource utilization effectively by server consolidation. In this paper, the concept of memory block and user satisfaction is redefined combined with user requirements. According to the unbalanced memory resource states and user preference requirements in multi-virtual machine environments, a model of proper memory resource allocation is proposed combined with memory block and user satisfaction, and at the same time a memory optimization allocation algorithm is proposed which is based on virtual memory block, makespan and user satisfaction under the premise of an orderly physical nodes states also. In the algorithm, a memory optimal problem can be transformed into a resource workload balance problem. All the virtual machine tasks are simulated in Cloudsim platform. And the experimental results show that the problem of virtual machine memory resource allocation can be solved flexibly and efficiently.

Fixed-Length Allocation and Deallocation of Memory for Embedded Java Virtual Machine (임베디드 자바가상기계를 위한 고정 크기 메모리 할당 및 해제)

  • 양희재
    • Proceedings of the IEEK Conference
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    • pp.1335-1338
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    • 2003
  • Fixed-size memory allocation is one of the most promising way to avoid external fragmentation in dynamic memory allocation problem. This paper presents an experimental result of applying the fixed- size memory allocation strategy to Java virtual machine for embedded system. The result says that although this strategy induces another memory utilization problem caused by internal fragmentation, the effect is not very considerable and this strategy is well-suited for embedded Java system. The experiment has been performed in a real embedded Java system called the simpleRTJ.

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Automatic Dynamic Memory Management Techniques for Memory Scarce Java system (메모리가 적은 자바 시스템을 위한 자동 동적 메모리 관리 기법)

  • Choi, Hyung-Kyu;Moon, Soo-Mook
    • Journal of KIISE:Computer Systems and Theory
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    • v.35 no.8
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    • pp.378-384
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    • 2008
  • 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 of the Compression Algorithm for in-Memory Data of the Virtual Memory (가상 메모리 압축을 위한 CAMD 알고리즘 설계)

  • Jang, Seung-Ju
    • The KIPS Transactions:PartA
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    • v.11A no.3
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    • pp.157-162
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    • 2004
  • This paper suggests the CAMD(Compression Algorithm for in-Memory Data) algorithm that is not moved the pages into the swap space by assigning the compressed cache area in the main memory. The CAMD algorithm that supports the virtual memory system takes high memory usability and performance benefit by reducing the page fault. The memory data is not general data. It is extraordinary data format. In general it consists of specific form of data. Therefore. the CAMD algorithm can compress this data efficiently.

Symbiotic Dynamic Memory Balancing for Virtual Machines in Smart TV Systems

  • Kim, Junghoon;Kim, Taehun;Min, Changwoo;Jun, Hyung Kook;Lee, Soo Hyung;Kim, Won-Tae;Eom, Young Ik
    • ETRI Journal
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    • v.36 no.5
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    • pp.741-751
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    • 2014
  • Smart TV is expected to bring cloud services based on virtualization technologies to the home environment with hardware and software support. Although most physical resources can be shared among virtual machines (VMs) using a time sharing approach, allocating the proper amount of memory to VMs is still challenging. In this paper, we propose a novel mechanism to dynamically balance the memory allocation among VMs in virtualized Smart TV systems. In contrast to previous studies, where a virtual machine monitor (VMM) is solely responsible for estimating the working set size, our mechanism is symbiotic. Each VM periodically reports its memory usage pattern to the VMM. The VMM then predicts the future memory demand of each VM and rebalances the memory allocation among the VMs when necessary. Experimental results show that our mechanism improves performance by up to 18.28 times and reduces expensive memory swapping by up to 99.73% with negligible overheads (0.05% on average).

Implementation of Integrated CPU-GPU for Efficient Uniform Memory Access Method and Verification System (CPU-GPU간 긴밀성을 위한 효율적인 공유메모리 접근 방법과 검증 시스템 구현)

  • Park, Hyun-moon;Kwon, Jinsan;Hwang, Tae-ho;Kim, Dong-Sun
    • IEMEK Journal of Embedded Systems and Applications
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    • v.11 no.2
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    • pp.57-65
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    • 2016
  • In this paper, we propose a system for efficient use of shared memory between CPU and GPU. The system, called Fusion Architecture, assures consistency of the shared memory and minimizes cache misses that frequently occurs on Heterogeneous System Architecture or Unified Virtual Memory based systems. It also maximizes the performance for memory intensive jobs by efficient allocation of GPU cores. To test between architectures on various scenarios, we introduce the Fusion Architecture Analyzer, which compares OpenMP, OpenCL, CUDA, and the proposed architecture in terms of memory overhead and process time. As a result, Proposed fusion architectures show that the Fusion Architecture runs benchmarks 55% faster and reduces memory overheads by 220% in average.

A Study for Protecting the Virtual Memory of Applications (어플리케이션의 가상 메모리 보호를 위한 연구)

  • Kim, Dong-Ryul;Moon, Jong-sub
    • IEMEK Journal of Embedded Systems and Applications
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    • v.11 no.6
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    • pp.335-341
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    • 2016
  • As information technology advances rapidly, various smart devices are becoming an essential element in our lives. Smart devices are providing services to users through applications up on the operating system. Operating systems have a variety of rules, such as scheduling applications and controlling hardwares. Among those rules, it is significant to protect private information in the information-oriented society. Therefore, isolation task, that makes certain memory space separated for each application, should highly be guaranteed. However, modern operating system offers the function to access the memory space from other applications for the sake of debugging. If this ability is misused, private information can be leaked or modified. Even though the access authority to memory is strictly managed, there exist cases found exploited. In this paper, we analyze the problems of the function provided in the Android environment that is the most popular and opened operating system. Also, we discuss how to avoid such kind of problems and verify with experiments.

A Dynamic Allocation Scheme for Improving Memory Utilization in Xen (Xen에서 메모리 이용률 향상을 위한 동적 할당 기법)

  • Lee, Kwon-Yong;Park, Sung-Yong
    • Journal of KIISE:Computer Systems and Theory
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    • v.37 no.3
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    • pp.147-160
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    • 2010
  • The system virtualization shows interest in the consolidation of servers for the efficient utilization of system resources. There are many various researches to utilize a server machine more efficiently through the system virtualization technique, and improve performance of the virtualization software. These researches have studied with the activity to control the resource allocation of virtual machines dynamically focused on CPU, or to manage resources in the cross-machine using the migration. However, the researches of the memory management have been wholly lacking. In this respect, the use of memory is limited to allocate the memory statically to virtual machine in server consolidation. Unfortunately, the static allocation of the memory causes a great quantity of the idle memory and decreases the memory utilization. The underutilization of the memory makes other side effects such as the load of other system resources or the performance degradation of services in virtual machines. In this paper, we suggest the dynamic allocation of the memory in Xen to control the memory allocation of virtual machines for the utilization without the performance degradation. Using AR model for the prediction of the memory usage and ACO (Ant Colony Optimization) algorithm for optimizing the memory utilization, the system operates more virtual machines without the performance degradation of servers. Accordingly, we have obtained 1.4 times better utilization than the static allocation.

Transient Overloads Control Mechanism for Virtual Memory System (가상 메모리 시스템의 일시적인 과부하 완화 기법)

  • Go, Young-Woong;Lee, Jae-Yong;Hong, Cheol-Ho;Yu, Hyukc
    • The KIPS Transactions:PartA
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    • v.8A no.4
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    • pp.319-330
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    • 2001
  • In virtual memory system, when a process attempts to access a page that is not resident in memory, the system generates and handles a page fault that causes unpredictable delay. So virtual memory system is not appropriate for the real-time system, because it can increase the deadline miss ratio of real-time task. In multimedia system, virtual memory system may degrade the QoS(quality of service) of multimedia application. Furthermore, in general-purpose operating system, whenever a new task is dynamically loaded, virtual memory system suffers from extensive page fault that cause transient overloading state. In this paper, we present efficient overloading control mechanism called RBPFH (Rate-Based Page Fault Handling). A significant feature of the RBPFH algorithm is page fault dispersion that keeps page fault ratio from exceeding available bound by monitoring current system resources. Furthermore, whenever the amount of available system resource is changed, the RBPFH algorithm dynamically adjusts the page fault handling rate. The RBPFH algorithm is implemented in the Linux operating system and its performance measured. The results demonstrate RBPFH\`s superior performance in supporting multimedia applications. Experiment result shows that RBPFH could achieve 10%∼20% reduction in deadline miss ratio and 50%∼60% reduction in average delay.

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