16841890
Scheduling Scheme based on Dedication Rate in Volunteer Computing Environment
A volunteer node can join and leave a volunteer computing system freely. However, existing volunteer computing systems suffer from interruptions of job execution, delays of execution time, and increases of total execution time, since they do not consider dynamic scheduling properties (i.e. volatilities), such as leave, join, and suspension. Therefore, dynamic execution properties of volunteer node should be considered in scheduling schemes, in order to design a stable and reliable volunteer computing system. This paper proposes a new scheduling scheme based on the dedication rate (DR), which reflects the dynamic properties of a volunteer. The scheduling scheme improves the completeness and reliability of execution, while also decreasing delay and total execution time. In addition, an implementation of the proposed scheduling scheme on top of Korea@Home is described, as well as performance evaluation
16177959
Multi-Node Global Directory Construction in Peer-to-Peer Systems
In P2P systems, the speed of searching for desired lists of sharable files is one of the most important measurement issues in evaluation of overall system performance. Although the searching schemes of existing non-structured P2P systems have been improved to enhance speed considerably, they still never reach to the level of those of the centralized and structured systems. In this paper, we propose a multi-node global directory in P2P systems, where all the lists of sharable resources of the joining peers are aggregated and divided into the chosen nodes while keeping collating sequence as a whole to make one big linked list. Thus in indexed sequential searching, the system provides us with convenience of using the command like 'dir' of MS-DOS, and in general keyword searching, which is naturally impossible for the structured P2P systems, the searching speed is even faster than those of centralized P2P systems since a small list segment is scanned at each node synchronously in parallel
14154834
Region-based stage construction protocol for fault tolerant execution of mobile agent
Fault tolerance is essential to the development of reliable mobile agent systems in order to guarantee continuous execution of mobile agents. For this purpose, previous work has proposed fault tolerant protocols for mobile agent execution based on stage construction. However, when previous protocols are applied to a multiregion mobile agent computing environment, the overhead of work such as monitoring, election, voting and agreement is increased. We propose a region-based stage construction (RBSC) protocol for fault tolerant execution of mobile agents in a multiregion mobile agent computing environment. The RBSC protocol uses new concepts of quasiparticipant and substage in order to put together some places located in different regions within a stage in the same region. Therefore, the RBSC protocol decreases the overhead of stage works. Consequently, the RBSC protocol decreases the total execution time of mobile agents.
34200542
MJSA: Markov job scheduler based on availability in desktop grid computing environment
In a desktop grid computing environment, voluntary desktops (i.e., resource providers) are free to leave and join independently in the middle of execution. To develop a reliable desktop grid computing system, a scheduling scheme must consider the dynamic nature (i.e., volatility) of volunteers. Existing desktop grid computing systems, however, do not consider volatility in their scheduling procedures. As a result, job execution is often suspended, resulting in delayed completion time and degraded performance and reliability. To solve these limitations, we propose the Markov Job Scheduler based on Availability (MJSA) supporting three advanced scheduling schemes: OPTIMIST, PESSIMIST, and REALIST. These scheduling schemes are based on stochastic modeling of desktop availability. In the OPTIMIST scheme, in which time constraints are relaxed, the MJSA provides reliable resource selection at low cost. In the PESSIMIST scheme, where time constraints are rigid, the MJSA enables stable makespan in strictly time. Finally, in the REALIST scheme, where time constraints are only partially relaxed, the MJSA provides enhanced cost efficiency. In conclusion, the MJSA improves performance and reliability by adapting the appropriate scheduling scheme when selecting volunteers according to the needs of applications.
41968338
Group-Based Scheduling Scheme for Result Checking in Global Computing Systems
This paper considers the problem of correctness to fault-tolerance in global computing systems. Global computing system has been shown to be exposed to intentional attacks, where authentication is not relevant, network security techniques are insufficient. To guarantee correctness for computation, fault-tolerance schemes have been used to majority voting and spot-checking but these schemes intend to high computation delay because are not applied scheduling scheme for result checking. In this paper, we propose a new technique called GBSS(Group-Based Scheduling Scheme) which guarantee correctness and reduce computation delay by using fault-tolerant scheduling scheme to the result checking. Additionally, simulation results show increased usable rate of the CPU and increased performance of the system.
17124028
Probabilistic Observation Prediction Model based E4 Scheduling Mechanism in Peer to Peer Grid Computing
Peer to peer (P2P) grid computing is an Internet-based parallel computing paradigm to achieve tremendous computing power by voluntary peers. Since peers are not dedicated to a system, peers are free to leave and join autonomously during computation in this computing environment. A scheduling mechanism must cover the volatility of peers to support a reliable P2P grid computing system. Most existing P2P grid computing systems, however, suffer from blocked job execution and delayed makespan because they do not consider the volatile features of peers in the scheduling procedure. In order to improve system reliability, we propose a probabilistic observation prediction (POP) -based EA scheduling mechanism supporting three advanced scheduling policies: loose time constraint policy (LTCP), strict time constraint policy (STCP), and hybrid time constraint policy (HTCP). LTCP is for general use, STCP aims at minimizing makespan, and HTCP attempts to improve efficiency, and performance-to-cost ratio. All policies are based on stochastic modeling of peer state transition while endeavoring to manage the volatile features of peers
13605710
Portable Haptic Display for Large Immersive Virtual Environments
This paper introduces Portable Haptic Display (PHD), a novel platform-independent haptic rendering system that can be conveniently integrated into a large immersive virtual environment while maximizing the individual reusability of haptic interfaces and visual displays. The PHD has an architecture of distributed rendering where two computers (or clusters of computers) are in charge of all computations needed for rendering with corresponding displays and share necessary information via network. We report the architecture, implementation details, and performance evaluation results of the PHD in this paper. The PHD is especially useful in places that have multiple haptic interfaces and large immersive visual displays and that need to use them together as well as individually, such as research laboratories, companies, and hospitals.
5975093
Multi-chain prefetching: effective exploitation of inter-chain memory parallelism for pointer-chasing codes
Presents multi-chain prefetching, a technique that utilizes offline analysis and a hardware prefetch engine to prefetch multiple independent pointer chains simultaneously, thus exploiting inter-chain memory parallelism for the purpose of memory latency tolerance. This paper makes three contributions. First, we introduce a scheduling algorithm that identifies independent pointer chains in pointer-chasing codes and computes a prefetch schedule that overlaps serialized cache misses across separate chains. Our analysis focuses an static traversals. We also propose using speculation to identify independent pointer chains in dynamic traversals. Second, we present the design of a prefetch engine that traverses pointer-based data structures and overlaps multiple pointer chains according to our scheduling algorithm. Finally, we conduct an experimental evaluation of multi-chain prefetching and compare its performance against two existing techniques: jump pointer prefetching and prefetch arrays. Our results show that multi-chain prefetching improves the execution time by 40% across six pointer-chasing kernels from the Olden benchmark suite and by 8% across four SPECInt CPU2000 benchmarks. Multi-chain prefetching also outperforms jump pointer prefetching and prefetch arrays by 28% on Olden, and by 12% on SPECInt. Furthermore, speculation can enable multi-chain prefetching for some dynamic traversal codes, but our technique loses its effectiveness when the pointer-chain traversal order is unpredictable. Finally, we also show that combining multi-chain prefetching with prefetch arrays can potentially provide higher performance than either technique alone.
29438564
Motion-compensated 3-D subband coding of video
This paper describes a video coding system based on motion-compensated three-dimensional (3-D) subband/wavelet coding (MC-3DSBC), which can overcome the limits of both 3-D SBC and MC prediction-based coding. In this new system, spatio-temporal subbands are generated by MC temporal analysis and a spatial wavelet transform, and then encoded by 3-D subband-finite state scalar quantization (3DSB-FSSQ). The rate allocation from the GOP level to each class of subbands is optimized by utilizing the structural property of MC-3DSBC that additive superposition approximately holds for both rate and distortion. The proposed video coding system is applied to several test video clips. Its performance exceeds that of both a known MPEG-1 implementation and a similar subband MC predictive coder while maintaining modest computational complexity and memory size.
9347832
Proxy location problems and their generalizations
In this paper we suggest a new angle to look on proxy location problems. We view the proxy as a service and generalize the problem of optimally placing proxies to optimally placing any service in the network. We differentiate between two cases: transparent services, such as transparent caches (TERCs), and non-transparent services where the end stations, such as hosts using a cache, need to be configured with respect to the service locations. This formulation enables us to study in a unified framework the location problems related to active networks, overlay peer-to-peer networks, as well as, CDNs and caching. For both cases we formalize the problem of optimally placing network servers and introduce approximation algorithms. We present simulation results of approximations and heuristics. We also present an optimal solution for the location problem for a special topology. We show, through a series of examples, that our approach can be applied to a variety of different services.
2658837
A general framework for prefetch scheduling in linked data structures and its application to multi-chain prefetching
Pointer-chasing applications tend to traverse composite data structures consisting of multiple independent pointer chains. While the traversal of any single pointer chain leads to the serialization of memory operations, the traversal of independent pointer chains provides a source of memory parallelism. This article investigates exploiting such interchain memory parallelism for the purpose of memory latency tolerance, using a technique called multi--chain prefetching. Previous works [Roth et al. 1998;Roth and Sohi 1999] have proposed prefetching simple pointer-based structures in a multi--chain fashion. However, our work enables multi--chain prefetching for arbitrary data structures composed of lists, trees, and arrays.This article makes five contributions in the context of multi--chain prefetching. First, we introduce a framework for compactly describing linked data structure (LDS) traversals, providing the data layout and traversal code work information necessary for prefetching. Second, we present an off-line scheduling algorithm for computing a prefetch schedule from the LDS descriptors that overlaps serialized cache misses across separate pointer-chain traversals. Our analysis focuses on static traversals. We also propose using speculation to identify independent pointer chains in dynamic traversals. Third, we propose a hardware prefetch engine that traverses pointer-based data structures and overlaps multiple pointer chains according to the computed prefetch schedule. Fourth, we present a compiler that extracts LDS descriptors via static analysis of the application source code, thus automating multi--chain prefetching. Finally, we conduct an experimental evaluation of compiler-instrumented multi--chain prefetching and compare it against jump pointer prefetching [Luk and Mowry 1996], prefetch arrays [Karlsson et al. 2000], and predictor-directed stream buffers (PSB) [Sherwood et al. 2000].Our results show compiler-instrumented multi--chain prefetching improves execution time by 40% across six pointer-chasing kernels from the Olden benchmark suite [Rogers et al. 1995], and by 3% across four SPECint2000 benchmarks. Compared to jump pointer prefetching and prefetch arrays, multi--chain prefetching achieves 34% and 11% higher performance for the selected Olden and SPECint2000 benchmarks, respectively. Compared to PSB, multi--chain prefetching achieves 27% higher performance for the selected Olden benchmarks, but PSB outperforms multi--chain prefetching by 0.2% for the selected SPECint2000 benchmarks. An ideal PSB with an infinite Markov predictor achieves comparable performance to multi--chain prefetching, coming within 6% across all benchmarks. Finally, speculation can enable multi--chain prefetching for some dynamic traversal codes, but our technique loses its effectiveness when the pointer-chain traversal order is highly dynamic.