The Experts below are selected from a list of 78 Experts worldwide ranked by ideXlab platform
Kishor S. Trivedi - One of the best experts on this subject based on the ideXlab platform.
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software aging in the eucalyptus cloud computing infrastructure characterization and rejuvenation
ACM Journal on Emerging Technologies in Computing Systems, 2014Co-Authors: Jean Araujo, Vieira F. De Souza, Rivalino Matias, Rubens Matos, Vandi Alves, Paulo Romero Martins Maciel, Kishor S. TrivediAbstract:The need for high reliability, availability and performance has significantly increased in modern applications, that handle rapidly growing demands while providing uninterruptible services. Cloud computing systems fundamentally provide access to large pools of data and computational resources. Eucalyptus is a software framework largely used to implement private clouds and hybrid-style Infrastructure as a Service. It implements the Amazon Web Service (AWS) API, allowing interoperability with other AWS-based services. This article investigates the software aging effects in the Eucalyptus framework, considering workloads composed of intensive requests for remote storage attachment and virtual machine instantiations. We found problems that may be harmful to system dependability and performance, specifically regarding to RAM memory and Swap Space exhaustion, besides highly excessive CPU utilization by the virtual machines. We also present an approach that applies time series analysis to schedule rejuvenation, so as to reduce the downtime by predicting the proper moment to perform the rejuvenation. We experimentally evaluate our approach using an Eucalyptus test bed. The results show that our approach achieves higher availability, when compared to a threshold-triggered rejuvenation method based on continuous monitoring of resources utilization.
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software aging in the eucalyptus cloud computing infrastructure characterization and rejuvenation
ACM Journal on Emerging Technologies in Computing Systems, 2014Co-Authors: Jean Araujo, Vieira F. De Souza, Rivalino Matias, Rubens Matos, Vandi Alves, Paulo Romero Martins Maciel, Kishor S. TrivediAbstract:The need for high reliability, availability and performance has significantly increased in modern applications, that handle rapidly growing demands while providing uninterruptible services. Cloud computing systems fundamentally provide access to large pools of data and computational resources. Eucalyptus is a software framework largely used to implement private clouds and hybrid-style Infrastructure as a Service. It implements the Amazon Web Service (AWS) API, allowing interoperability with other AWS-based services. This article investigates the software aging effects in the Eucalyptus framework, considering workloads composed of intensive requests for remote storage attachment and virtual machine instantiations. We found problems that may be harmful to system dependability and performance, specifically regarding to RAM memory and Swap Space exhaustion, besides highly excessive CPU utilization by the virtual machines. We also present an approach that applies time series analysis to schedule rejuvenation, so as to reduce the downtime by predicting the proper moment to perform the rejuvenation. We experimentally evaluate our approach using an Eucalyptus test bed. The results show that our approach achieves higher availability, when compared to a threshold-triggered rejuvenation method based on continuous monitoring of resources utilization.
Ohhoon Kwon - One of the best experts on this subject based on the ideXlab platform.
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Swap Space management technique for portable consumer electronics with nand flash memory
IEEE Transactions on Consumer Electronics, 2010Co-Authors: Ohhoon KwonAbstract:Flash memory has more capacity and a lower price. It makes flash memory more suitable for portable consumer electronics. Portable consumer electronics such as table PC and smart phones use NAND flash memory as a secondary storage because it has many attractive features such as small size, fast access speeds, and light weight. The portable consumer electronics with NAND flash memory exploit a "demand paging" to run applications, and also use a "Swapping" to extend a limited main memory Space. However, if the portable consumer electronics use NAND flash memory as Swap Space, it should perform garbage collection, which is a time-consuming operation. Therefore, in order to manage Swap Space efficiently, this work presents a novel garbage collection policy for the portable consumer electronics with a Swap system. The proposed policy has three features important in NAND flash memory based Swap systems: (1) long endurance of NAND flash memory, (2) quick garbage collection, and (3) low energy consumption.
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Swapping strategy to improve i o performance of mobile embedded systems using compressed file systems
Embedded and Real-Time Computing Systems and Applications, 2008Co-Authors: Ohhoon Kwon, Yunjung Yoo, Kern KohAbstract:Compressed file systems are suitable for mobile embedded systems with small capacity of storage systems because the contents of files are stored in a compressed form to save the Space of storage in the compressed file systems. Therefore a data should be decompressed before it is accessed by an application program. That is a computational overhead of compressed file systems. Furthermore, the mobile embedded systems exploit demand paging mechanism to cut down their cost and size as well as the compressed file systems. And also, to extend a main memory Space, the mobile embedded systems use "Swapping" mechanism which stores the data evicted from a main memory in a Swap area, and serves the data when the application requests it again. In this paper, we propose the new Swapping strategy for the mobile embedded systems using the compressed file systems, which aims to keep the decompressed data of compressed file systems in the Swap Space and serves them directly from the Swap Space if necessary. This strategy reduces several copying overhead and decompressing operation of compressed file systems. As a result, it could improve the I/O performance of mobile embedded systems. Trace-driven simulations show that the proposed strategy performs better than existing Swapping mechanism in terms of the total I/O performance, page fault ratio, and page fault latency.
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Swap aware garbage collection for nand flash memory based embedded systems
Computer and Information Technology, 2007Co-Authors: Ohhoon KwonAbstract:Embedded systems use NAND flash memory as a secondary storage device because it has many attractive features such as small size, fast access speeds, shock resistance, and light weight. NAND flash memory based embedded systems exploit a "demand paging" to run applications and also use a "Swapping" to extend a limited main memory Space. Because the embedded systems use NAND flash memory as Swap Space, it should perform garbage collection, which is a time-consuming operation. Besides, the number of the erase operations allowed to each block is also limited. In this paper, we propose a new garbage collection policy for embedded systems with the Swap system. The proposed garbage collection policy focuses on minimizing the garbage collection time and even wear-leveling. Trace-driven simulations show that the proposed policy performs better than existing garbage collection policies in terms of the garbage collection time and the endurance of flash memory.
Hyoungjoo Kim - One of the best experts on this subject based on the ideXlab platform.
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seof an adaptable object prefetch policy for object oriented database systems
International Conference on Data Engineering, 1997Co-Authors: Jungho Ahn, Hyoungjoo KimAbstract:The performance of object access can be drastically improved by an efficient object prefetch policy. In this paper, we present a new prefetch policy, called Selective Eager Object Fetch (SEOF), which prefetches objects only from selected candidate pages without using any high-level object semantics. Our policy considers both the correlations and the frequencies of fetching objects. Unlike existing prefetch policies, this policy utilizes the memory and the Swap Space of clients efficiently without resource exhaustion. Furthermore, the proposed policy has good adaptability to both the effectiveness of clustering and the database size. We show the performance of the proposed policy through experiments over various multi-client system configurations.
Ke Liu - One of the best experts on this subject based on the ideXlab platform.
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Synergistic Coupling of SSD and Hard Disk for QoS-aware Virtual Memory
2013Co-Authors: Ke Liu, Xuechen Zhang, Kei Davis, Song JiangAbstract:Abstract—With significant advantages in capacity, power consumption, and price, solid state disk (SSD) has good potential to be employed as an extension of DRAM (memory), such that applications with large working sets could run efficiently on a modestly configured system. While initial results reported in recent works show promising prospects for this use of SSD by incorporating it into the management of virtual memory, frequent writes from write-intensive programs could quickly wear out SSD, making the idea less practical. We propose a scheme, HybridSwap, that integrates a hard disk with an SSD for virtual memory management, synergistically achieving the advantages of both. In addition, HybridSwap can constrain performance loss caused by Swapping according to user-specified QoS requirements. To minimize writes to the SSD without undue performance loss, HybridSwap sequentially Swaps a set of pages of virtual memory to the hard disk if they are expected to be read together. Using a history of page access patterns HybridSwap dynamically creates an out-of-memory virtual memory page layout on the Swap Space spanning the SSD and hard disk such that random reads are served by SSD and sequential reads are asynchronously served by the hard disk with high efficiency. In practice HybridSwap can effectively exploit the aggregate bandwidth of the two devices to accelerate page Swapping. We have implemented HybridSwap in a recent Linux kernel, version 2.6.35.7. Our evaluation with representative benchmarks, such as Memcached for key-value store, and scientific programs from the ALGLIB cross-platform numerical analysis and data processing library, shows that the number of writes to SSD can be reduced by 40 % with the system’s performance comparable to that with pure SSD Swapping, and can satisfy a Swapping-related QoS requirement as long as the I/O resource is sufficient. Keywords-SSD; Page Swapping; and Flash Endurance. I
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synergistic coupling of ssd and hard disk for qos aware virtual memory
International Symposium on Performance Analysis of Systems and Software, 2013Co-Authors: Ke Liu, Xuechen Zhang, Kei Davis, Song JiangAbstract:With significant advantages in capacity, power consumption, and price, solid state disk (SSD) has good potential to be employed as an extension of DRAM (memory), such that applications with large working sets could run efficiently on a modestly configured system. While initial results reported in recent works show promising prospects for this use of SSD by incorporating it into the management of virtual memory, frequent writes from write-intensive programs could quickly wear out SSD, making the idea less practical. We propose a scheme, HybridSwap, that integrates a hard disk with an SSD for virtual memory management, synergistically achieving the advantages of both. In addition, HybridSwap can constrain performance loss caused by Swapping according to user-specified QoS requirements. To minimize writes to the SSD without undue performance loss, HybridSwap sequentially Swaps a set of pages of virtual memory to the hard disk if they are expected to be read together. Using a history of page access patterns HybridSwap dynamically creates an out-of-memory virtual memory page layout on the Swap Space spanning the SSD and hard disk such that random reads are served by SSD and sequential reads are asynchronously served by the hard disk with high efficiency. In practice HybridSwap can effectively exploit the aggregate bandwidth of the two devices to accelerate page Swapping. We have implemented HybridSwap in a recent Linux kernel, version 2.6.35.7. Our evaluation with representative benchmarks, such as Memcached for key-value store, and scientific programs from the ALGLIB cross-platform numerical analysis and data processing library, shows that the number of writes to SSD can be reduced by 40% with the system's performance comparable to that with pure SSD Swapping, and can satisfy a Swapping-related QoS requirement as long as
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Synergistically Coupling Of Solid State Drives And Hard Disks For Qos-Aware Virtual Memory
DigitalCommons@WayneState, 2013Co-Authors: Ke LiuAbstract:With significant advantages in capacity, power consumption, and price, solid state disk (SSD) has good potential to be employed as an extension of dynamic random-access memory, such that applications with large working sets could run efficiently on a modestly configured system. While initial results reported in recent works show promising prospects for this use of SSD by incorporating it into the management of virtual memory, frequent writes from write-intensive programs could quickly wear out SSD, making the idea less practical. This thesis makes four contributions towards solving this issue. First, we propose a scheme, HybridSwap, that integrates a hard disk with an SSD for virtual memory man-agement, synergistically achieving the advantages of both. In addition, HybridSwap can constrain performance loss caused by Swapping according to user-specified QoS requirements. Second, We develop an efficient algorithm to record memory access history and to identify page access sequences and evaluate their locality. Using a history of page access patterns HybridSwap dynamically creates an out-of-memory virtual memory page layout on the Swap Space spanning the SSD and hard disk such that random reads are served by SSD and sequential reads are asynchronously served by the hard disk with high efficiency. Third, we build a QoS-assurance mechanism into HybridSwap to demonstrate the flexibility of the system in bounding the performance penalty due to Swapping. It allows users to specify a bound on the program stall time due to page faults as a percentage of the program\u27s total run time. Forth, we have implemented HybridSwap in a recent Linux kernel, version 2.6.35.7. Our evaluation with representative benchmarks, such as Memcached for key-value store, and scientific programs from the ALGLIB cross-platform numerical analysis and data processing library, shows that the number of writes to SSD can be reduced by 40% with the system\u27s performance comparable to that with pure SSD Swapping, and can satisfy a Swapping-related QoS requirement as long as the I/O resource is sufficient
Jean Araujo - One of the best experts on this subject based on the ideXlab platform.
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software aging in the eucalyptus cloud computing infrastructure characterization and rejuvenation
ACM Journal on Emerging Technologies in Computing Systems, 2014Co-Authors: Jean Araujo, Vieira F. De Souza, Rivalino Matias, Rubens Matos, Vandi Alves, Paulo Romero Martins Maciel, Kishor S. TrivediAbstract:The need for high reliability, availability and performance has significantly increased in modern applications, that handle rapidly growing demands while providing uninterruptible services. Cloud computing systems fundamentally provide access to large pools of data and computational resources. Eucalyptus is a software framework largely used to implement private clouds and hybrid-style Infrastructure as a Service. It implements the Amazon Web Service (AWS) API, allowing interoperability with other AWS-based services. This article investigates the software aging effects in the Eucalyptus framework, considering workloads composed of intensive requests for remote storage attachment and virtual machine instantiations. We found problems that may be harmful to system dependability and performance, specifically regarding to RAM memory and Swap Space exhaustion, besides highly excessive CPU utilization by the virtual machines. We also present an approach that applies time series analysis to schedule rejuvenation, so as to reduce the downtime by predicting the proper moment to perform the rejuvenation. We experimentally evaluate our approach using an Eucalyptus test bed. The results show that our approach achieves higher availability, when compared to a threshold-triggered rejuvenation method based on continuous monitoring of resources utilization.
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software aging in the eucalyptus cloud computing infrastructure characterization and rejuvenation
ACM Journal on Emerging Technologies in Computing Systems, 2014Co-Authors: Jean Araujo, Vieira F. De Souza, Rivalino Matias, Rubens Matos, Vandi Alves, Paulo Romero Martins Maciel, Kishor S. TrivediAbstract:The need for high reliability, availability and performance has significantly increased in modern applications, that handle rapidly growing demands while providing uninterruptible services. Cloud computing systems fundamentally provide access to large pools of data and computational resources. Eucalyptus is a software framework largely used to implement private clouds and hybrid-style Infrastructure as a Service. It implements the Amazon Web Service (AWS) API, allowing interoperability with other AWS-based services. This article investigates the software aging effects in the Eucalyptus framework, considering workloads composed of intensive requests for remote storage attachment and virtual machine instantiations. We found problems that may be harmful to system dependability and performance, specifically regarding to RAM memory and Swap Space exhaustion, besides highly excessive CPU utilization by the virtual machines. We also present an approach that applies time series analysis to schedule rejuvenation, so as to reduce the downtime by predicting the proper moment to perform the rejuvenation. We experimentally evaluate our approach using an Eucalyptus test bed. The results show that our approach achieves higher availability, when compared to a threshold-triggered rejuvenation method based on continuous monitoring of resources utilization.
