Internet visitors can be well protected by hiding their traces. The purpose of traditional traceability is to obtain the user's IP address and physical location through some technical means. However, the essence o...
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ISBN:
(纸本)9781665414852
Internet visitors can be well protected by hiding their traces. The purpose of traditional traceability is to obtain the user's IP address and physical location through some technical means. However, the essence of anti-traceability is to hide information browsing and search intention through trace hiding technology. Inspired by the PPM (Probability Packet Marking) strategy, an effective method of anti-tracing is to prevent the attacker from reconstructing the user's access path in a VPN network. We investigate a systematic study of ant-itracing to capture the relationship between resource allocation and security level guarantee in this paper. Furthermore, we propose a novel resource allocation and link scheduling algorithm with guaranteed security level. Numerical results verify that our proposed resource allocation solution can achieve good performance in terms of anti-tracing and security level guarantee.
We introduce the research overview of the practical imprecise computation model to achieve imprecise real-time applications. The practical imprecise computation model has multiple mandatory parts as real-time parts an...
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ISBN:
(纸本)9781479944309
We introduce the research overview of the practical imprecise computation model to achieve imprecise real-time applications. The practical imprecise computation model has multiple mandatory parts as real-time parts and multiple optional parts as non-real-time parts. We explain a new concept of real-time scheduling in the practical imprecise computation model, called semi-fixed-priority scheduling. In addition, we explain a semi-fixed-priority scheduling algorithm, called Rate Monotonic with Wind-up Part (RMWP). RMWP schedules each part in the practical imprecise computation model in Rate Monotonic order. We also introduce a real-time operating system for semi-fixed-priority scheduling algorithms, called RT-Est. We describe programming paradigms for the practical imprecise computation model in RT-Est. RT-Est has the SIM architecture for simulating real-time scheduling algorithms and the visualization tool for drawing simulation results. Finally we give future research directions for the practical imprecise computation model in theory and practice.
On many computers, a request to run a job is not serviced immediately but instead is placed in a queue and serviced only when resources are released by preceding jobs. In this paper, we build on runtime prediction tec...
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ISBN:
(纸本)3540666761
On many computers, a request to run a job is not serviced immediately but instead is placed in a queue and serviced only when resources are released by preceding jobs. In this paper, we build on runtime prediction techniques that we developed in previous research to explore two problems. The first problem is to predict how long applications will wait in a queue until they receive resources. We develop runtime estimates that result in more accurate wait-time predictions than other run-time prediction techniques. The second problem we investigate is improving scheduling performance. We use run-time predictions to improve the performance of the least-work-first and backfill scheduling algorithms. We find that using our run-time predictor results in lower mean wait times for the workloads with higher offered loads and for the backfill scheduling algorithm.
Time-Sensitive Networking (TSN) introduces standardized mechanisms that add real-time capabilities to IEEE 802.1 Ethernet networks. In particular, the Time-Aware Shaper (TAS) can be used to send frames in a determinis...
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ISBN:
(纸本)9781728152974
Time-Sensitive Networking (TSN) introduces standardized mechanisms that add real-time capabilities to IEEE 802.1 Ethernet networks. In particular, the Time-Aware Shaper (TAS) can be used to send frames in a deterministic fashion according to a predefined global schedule. Existing methods for generating the global communication schedule enforce isolation either in the time or in the space domain. This extended abstract presents a novel, more flexible window-based scheduling algorithm which removes the previously required isolation constraints for Scheduled Traffic (ST) by integrating worst-case delay analysis to guarantee bounded latency.
For high mobility users in a 5G NR network, interference management becomes a big challenge. Efficient RRM (Radio Resource Management) plays a primary role in increasing the Signal to Interference and Noise Ratio (SIN...
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ISBN:
(纸本)9781665422093
For high mobility users in a 5G NR network, interference management becomes a big challenge. Efficient RRM (Radio Resource Management) plays a primary role in increasing the Signal to Interference and Noise Ratio (SINR) values, and also in decreasing signal Transport Block Error Rate (TBER). To this end, the evaluation of these two parameters actively participates in the propagation channel sensitivity prediction. Thus, radio resources allocation must be efficient and powerful. Therefore, eight scheduling algorithms were developed and programmed into the mmWave model of NS-3 simulator. The simulations were run for different types of data flows, and the achieved results were evaluated in terms of SINR and TBER. The performance of most schemes in a typical 5G NR environment is satisfactory. In terms of SINR, and for the RT (Real Time) flows, MLWDF, EXP-Rule and our algorithm EXP-MLWDF ensure more reliability compared to other schemes, with values of around 25 dB for VOIP traffic and around 30 dB for video streams, whereas PF and Max-Rate allow better values for BE flows, with achievements greater than 20 dB, which presents improvements of about 60% compared to other schemes. On the other hand, PF, EXP-PF, EXP-Rule, Log-Rule and EXP-MLWDF ensure optimal values of TBER for RT flows, by achieving stable performance with a rate of less than 0.5% for VOIP, and around 0.1% for Vi5G. These values represent a reduction of 100% compared to other scheduling strategies. For NRT (Non-RT) flows, EXP-Rule and MLWDF have the best achievements and they quickly reach stability, with values between 0.4 and 1.4%, which represents an improvement of 70% in comparison with the concurrent schemes.
scheduling exams at universities can be formulated as a combinatorial optimization problem. Basically one has to schedule a certain number of exams in a given number of time periods so that a predetermined objective f...
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ISBN:
(纸本)9783540773443
scheduling exams at universities can be formulated as a combinatorial optimization problem. Basically one has to schedule a certain number of exams in a given number of time periods so that a predetermined objective function is minimized. In particular, the objective function penalizes schedules where students have to write exams in consecutive periods or even in the same period. Ant colony approaches have been demonstrated to be a powerful solution approach for various combinatorial optimization problems. This paper presents two ant colony approaches for the exam timetabling problem, a Max-Min and an ANTCOL approach. Using the Toronto benchmark test cases from the literature, both algorithms arc compared to other timetabling heuristics. Finally, the Max-Min and ANTCOL algorithms are compared using the same set of test cases. In spite of some shortcomings, the ANTCOL approach turned out to be a worthwhile algorithm, among the best currently in use for examination timetabling.
We consider the network control problem for wireless networks with How level dynamics under the general k-hop interference model. In particular, we investigate the control problem in low load and high load regimes. In...
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ISBN:
(纸本)9781424422463
We consider the network control problem for wireless networks with How level dynamics under the general k-hop interference model. In particular, we investigate the control problem in low load and high load regimes. In the low load regime, we show that the network can be stabilized by a regulated maximal scheduling policy considering flow level dynamics if the offered load satisfies a constraining bound condition. Because maximal matching is a general scheduling rule whose implementation is not specified, we propose a constant-time and distributed scheduling algorithm for a general k-hop interference model which can approximate the maximal scheduling policy within an arbitrarily small error. Under the stability condition, we show how to calculate transmission rates for different user classes such that the long-term (time average) network utility is maximized. Our results imply that congestion control is unnecessary when the offered load is low and optimal user rates can be determined to maximize users' long-term satisfaction. In the high load regime where the network can be unstable under the regulated maximal scheduling policy, we propose the cross-layer congestion control and scheduling algorithm which can stabilize the network under arbitrary network load. Through numerical analysis for some typical networks, we show that the proposed scheduling algorithm has much lower overhead than other existing queue-length-based constant-time scheduling schemes in the literature, and it achieves performance much better than the guaranteed bound. In addition, using congestion control in the low load condition results in much lower average utility compared to that due to the optimal transmission rate derived in the paper.
OpenMP is widely used for shared memory parallel programming and is especially useful for the parallelisation of loops. When it comes to task parallelism, however, OpenMP is less powerful and the sections construct la...
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ISBN:
(数字)9783540693031
ISBN:
(纸本)9783540693024
OpenMP is widely used for shared memory parallel programming and is especially useful for the parallelisation of loops. When it comes to task parallelism, however, OpenMP is less powerful and the sections construct lacks support for dependences and fine grained tasks. This paper proposes a new work-sharing construct, tasks, which is a generalisation of sections. It goes beyond sections by allowing unbalanced and finer grained tasks with arbitrary dependence structure. A proof-of-concept compiler has been implemented for the new directives, which includes a state-of-the-art scheduling algorithm for task graphs. Experiments with a large set of programs were conducted using the new directives. The results demonstrate that the new approach can efficiently exploit the task parallelism inherent in the code, without introducing any additional overhead.
Hybrid storage systems can fully leverage the advantages of multiple devices to achieve better performance. However, current systems are designed primarily for a slow disk with an expensive fast device at high costs. ...
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ISBN:
(纸本)9798350342918
Hybrid storage systems can fully leverage the advantages of multiple devices to achieve better performance. However, current systems are designed primarily for a slow disk with an expensive fast device at high costs. They ignore device features and workload status while placing data. The issue of cache pollution is affecting their data hotness identification. Besides, inconsistent load status in multiple devices is overlooked during migration. These shortcomings constrain the overall performance of the system. To solve this, we propose HyF2FS, a hybrid storage filesystem based on F2FS. HyF2FS features a cache-tiering integrated architecture that stores hot data and metadata in an accelerator while asynchronously migrating cold data to the SSD, which provides cost-effective opportunities to optimize device parallelism. HyF2FS uses multidimensional scores to place data on the appropriate device to achieve high bandwidth. To improve data hotness identification, HyF2FS proposes two-level counters. Besides, a migration window is employed to minimize the impact of migration on foreground I/O. By implementing these scheduling algorithms, HyF2FS can fully exploit the parallelism of both fast and slow devices. Experimental results demonstrate significant improvements in throughput (116%-244%) and latency reduction (49%-64%) compared to F2FS and other hybrid storage systems.
Real-time scheduling algorithms for multiprocessor systems have been the subject of considerable recent interest. For such an algorithm to be truly useful in practice, support for semaphore-based locking must be provi...
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ISBN:
(纸本)9780769529752
Real-time scheduling algorithms for multiprocessor systems have been the subject of considerable recent interest. For such an algorithm to be truly useful in practice, support for semaphore-based locking must be provided. However for man), global scheduling algorithms, no such mechanisms have been proposed. Furthermore, in the partitioned case, most prior semaphore schemes are either inefficient or restrict critical sections considerably In this paper a new flexible multiprocessor locking scheme is presented that can be applied under both partitioning and global scheduling. This scheme allows unrestricted critical-section nesting, but has been designed to deal with the common case of short non-nested accesses efficiently.
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