272767
A Real-Time Network Traffic Profiling System
This paper presents the design and implementation of a real-time behavior profiling system for high-speed Internet links. The profiling system uses flow-level information from continuous packet or flow monitoring systems, and uses data mining and information-theoretic techniques to automatically discover significant events based on the communication patterns of end-hosts. We demonstrate the operational feasibility of the system by implementing it and performing extensive benchmarking of CPU and memory costs using a variety of packet traces from OC-48 links in an Internet backbone network. To improve the robustness of this system against sudden traffic surges such as those caused by denial of service attacks or worm outbreaks, we propose a simple yet effective filtering algorithm. The proposed algorithm successfully reduces the CPU and memory cost while maintaining high profiling accuracy.
26849829
A Note on Optical Network with Nonsplitting Nodes
We study the problem of computing the minimum total weight multicast route in an optical network with both nonsplitting and splitting nodes, and present a simple approximation with performance ratio 3, which is better than existing one in the literature.
30316270
Connected Dominating Set
1931354
Coverage problems in wireless sensor networks: designs and analysis
One fundamental problem in wireless sensor networks is the coverage problem, which reflects the quality of service that can be provided by a particular sensor network. The coverage problem is defined from several points of view due to a variety of sensor networks and a wide-range of their applications. Several different designs and formulations of the coverage problem have been proposed. They are subject to various topics such as types of interest regions (areas versus targets) and different network constraints, such as fault tolerance and bandwidth limitation. In this paper, we survey the state-of-the-art coverage formulations with an objective of maximising network lifetime. In particular, we present an overview and analysis of the solutions proposed in recent research literature.
7378924
Minimum Coverage Breach and Maximum Network Lifetime in Wireless Sensor Networks
Network lifetime is a critical issue in Wireless Sensor Networks. It is possible to extend network lifetime by organizing the sensors into a number of sensor covers. However, with the limited bandwidth, coverage breach (i.e, targets that are not covered) can occur if the number of available time-slots/channels is less than the number of sensors in a sensor cover. In this paper, we study a joint optimization problem in which the objective is to minimize the coverage breach as well as to maximize the network lifetime. We show a "trade-off" scheme by presenting two strongly related models, which aim to tradeoffs between the two conflicting objectives. The main approach of our models is organizing sensors into non-disjoint sets, which is different from the current most popular approach and can gain longer network lifetime as well as less coverage breach. We proposed two algorithms for the first model based on linear programming and greedy techniques, respectively. Then we transform these algorithms to solve the second model by revealing the strong connection between the models. Through numerical simulation, we showed the good performance of our algorithms and the pictures of the tradeoff scheme in variant scenarios, which coincide with theoretical analysis very well. It is also showed that our algorithms could obtain less breach rate than the one proposed in [2].
15244818
Fault tolerant topology control for one-to-all communications in symmetric wireless networks
This paper introduces the problem of fault tolerant topology control for one-to-all communications in symmetric wireless networks. We investigate two algorithms to address the problem, namely Minimum Weight-Based Algorithm (MWBA) and Nearest Neighbour Augmentation Algorithm (NNAA) and prove that the former is a 4k approximation and the latter is a (k + 4) approximation. Through simulations, we evaluate the average performance of these two algorithms and find that MWBA is slightly better than NNAA in terms of the total power consumption.
6280828
Architecting Microprocessor Components in 3D Design Space
Interconnect is one of the major concerns in current and future microprocessor designs from both performance and power consumption perspective. The emergence of three-dimensional (3D) chip architectures, with its intrinsic capability to reduce the wire length, is one of the promising solutions to mitigate the interconnect related issues. In this paper we implement a few components of a microprocessor using custom design to show the potential performance and power benefits achievable through 3D integration under thermal constraints. We also introduce a standard cell based 3D design flow which leverages the commercial 2D design tools. Using this design flow we provide performance results of wide range of arithmetic units in 3D, thus introducing a fast method to analyze the performance benefits of 3D designs. In contrast to prior work, which mostly investigates single components of a processor, our work takes multiple components into consideration and the experimental results are promising in terms of delay and power reductions. Complex designs in 3D that have equivalent performance compared to a simple 2D designs is taken for IPC improvement analysis. An IPC improvement of 11% shown for a microprocessor implemented in 2-strata 3D technology
5172777
Using MEMS-based storage in computer systems---MEMS storage architectures
As an emerging nonvolatile secondary storage technology, MEMS-based storage exhibits several desirable properties including high performance, high storage volumic density, low power consumption, low entry cost, and small form factor. However, MEMS-based storage provides a limited amount of storage per device and is likely to be more expensive than magnetic disk. Systems designers will therefore need to make trade-offs to achieve well-balanced designs. We present an architecture in which MEMS devices are organized into MEMS storage enclosures with online spares. Such enclosures are proven to be highly reliable storage building bricks with no maintenance during their economic lifetimes. We also demonstrate the effectiveness of using MEMS as another layer in the storage hierarchy, bridging the cost and performance gap between MEMS storage and disk. We show that using MEMS as a disk cache can significantly improve system performance and cost-performance ratio.
14007342
Variation-aware resource sharing and binding in behavioral synthesis
As technology scales, the delay uncertainty caused by process variations has become increasingly pronounced in deep submicron designs. In the presence of process variations, worst-case timing analysis may lead to overly conservative synthesis, and may end up using excess resources to guarantee design constraints. In this paper, we propose an efficient variation-aware resource sharing and binding algorithm in behavioral synthesis, which takes into account the performance variations for functional units. The performance yield, which is defined as the probability that the synthesized hardware meets the target performance constraints, is used to evaluate the synthesis result. An efficient metric called statistical performance improvement, is used to guide resource sharing and binding. The proposed algorithm is evaluated within a commercial synthesis framework that generates optimized RTL netlists from behavioral specifications. The effectiveness of the proposed algorithm is demonstrated with a set of industrial benchmark designs, which consist of blocks that are commonly used in wireless and image processing applications. The experimental results show that our method achieves an average 33% area reduction over traditional methods, which are based on the worst-case delay analysis, with an average 10% run time overhead.
9257983
File System Workload Analysis For Large Scientific Computing Applications
Parallel scientific applications require high-performance I/O support from underlying file systems. A comprehensive understanding of the expected workload is therefore essential for the design of high-performance parallel file systems. We re-examine the workload characteristics in parallel computing environments in the light of recent technology advances and new applications. We analyze application traces from a cluster with hundreds of nodes. On average, each application has only one or two typical request sizes. Large requests from several hundred kilobytes to several megabytes are very common. Although in some applications small requests account for more than 90% of all requests, almost all of the I/O data are transferred by large requests. All of these applications show bursty access patterns. More than 65% of write requests have inter-arrival times within one millisecond in most applications. By running the same benchmark on different file models, we also find that the write throughput of using an individual output file for each node exceeds that of using a shared file for all nodes by a factor of 5. This indicates that current file systems are not well optimized for file sharing.
7656968
Using MEMS-based storage to boost disk performance
Non-volatile storage technologies such as flash memory, magnetic RAM (MRAM), and MEMS-based storage are emerging as serious alternatives to disk drives. Among these, MEMS storage is predicted to be the least expensive and highest density, and at about 1 ms access times still considerably faster than hard disk drives. Like the other emerging non-volatile storage technologies, it is highly suitable for small mobile devices but it is expensive to replace hard drives entirely. Its non-volatility, dense storage, and high performance still make it an ideal candidate for the secondary storage subsystem. We examine the use of MEMS storage in the storage hierarchy and show that using a technique called MEMS caching disk, we can achieve 30-49% of the pure MEMS storage performance by using only a small amount (3% of the disk capacity) of MEMS storage in conjunction with a standard hard drive. The resulting system is ideally suited for commercial packaging with a small MEMS device included as part of a standard disk controller or paired with a disk.