Experimental performance evaluation of a virtual software router

Increasing attention has been recently devoted to software routers based on off-the-shelf hardware and open-source operating systems running on personal computer (PC) architectures. Today's high-end PCs PCI shared buses fit into the multi-gigabit-per-second routing segment, for a price much lower than that of commercial routers. However, commercially available Network Interface Cards (NICs) lack programmability, and require not only packets to cross the PCI bus twice, but also to process them in software by the operating system (OS), reducing routing performance. In this paper we discuss the design of an FPGA-based NIC that permits to overcome the limitations of commercial NICs and provide a detailed description of its implementation.

Always Best Packet Switching (ABPS) is a novel approach for wireless communications that enables mobile nodes, equipped with multiple network interface cards (NICs), to dynamically determine the most appropriate NIC to use. Using ABPS, a mobile node can seamlessly switch to a different NIC in order to get better performance, without causing communication interruptions at the application level. To make this possible, NICs are kept always active and a software monitor constantly probes the channels for available access points. While this ensures maximum connection availability, considerable energy may be wasted when no access points are available for a given NIC. In this paper we address this issue by investigating the use of an "oracle" able to provide information on network availability. This allows to dynamically switch on/off NICs based on reported availability, thus reducing the power consumption. We present a Markov model which allows us to estimate the impact of the oracle on the ABPS mechanism: results show that significant reduction in energy consumption can be achieved with minimal impact on connection availability. We conclude by describing a prototype implementation of the oracle based on Web services and geolocalization.

In a wireless mesh network (WMN) with a number of stationary wireless routers, the aggregate capacity can be increased when each router is equipped with multiple network interface cards (NICs) and each NIC is assigned to a distinct orthogonal frequency channel. In this paper, given the logical topology of the network, we mathematically formulate a crosslayer fair bandwidth sharing problem as a non-linear mixedinteger network utility maximization problem. An optimal joint design, based on exact binary linearization techniques, is proposed which leads to a global maximum. A near-optimal joint design, based on approximate dual decomposition techniques, is also proposed which is practical for deployment. Performance is assessed through several numerical examples in terms of network utility, aggregate network throughput, and fairness index. Results show that our proposed designs can lead to multi-channelWMNs which are more efficient and fair compared to their singlechannel counterparts. The performance gain on both efficiency and fairness increase as the number of available NICs per router or the number of available frequency channels increases.

peer reviewed

System component failure – hardware and software, permanent and transient – are an integral part of the life cycle of any computer system. The degree to which a system suffers from these failures depends on factors such as system complexity, system design and implementation, and system size. These errors may lead to catastrophic application failure (termination of an application run with a CPU failure), silent application errors (such as network data corruption), or application hangs (such as when network interface card (NIC) malfunction), all wasting valuable computer time. For certain classes of computer systems, dealing with these failures is a requirement to provide a simulation environment reliable enough to meet end-user needs. Also, the more automated these solutions are, requiring minimal or no end-user intervention, the more likely they are to be used to achieve the required application stability. Dealing with failure, or fault tolerance, while minimizing application performance degradation, is an active research area, with no consensus as to what are optimal solution strategies, or even what failures need to be considered. Errors include items such as transient data transmission errors (dropped or corrupt packets), transient and permanent network failures (NIC), and process failure, to list a few. The current MPI standard addresses a limited number of failure scenarios, with application termination being the default response to failure. While the standard provide a mechanism for users to override this default response, it does not define error codes that provide information on system level failures – hardware or software. None-the-less, these need to be addressed to provide end-users with systems that meet their computing needs. Building on experience gained in the LA-MPI, FT-MPI, and LAM/MPI projects, the Open MPI collaboration has implemented, and is continuing to implement optional solutions that deal with a number of failure scenarios, to decrease the application mean-time-to-failure rate, to acceptable rates. The types of errors currently being dealt with include transient network data transmission errors, transient and permanent NIC failures, and process failure. The talk will discuss fault detection, fault recovery methods, and the degree to which applications need to be modified to benefit fromthese, if any. In addition, the performance impact of these solutions on several applications will be discussed.

The Cloud-RAN architecture is a key enabler to building future mobile networks in a flexible and cost-efficient way. For instance, switched Ethernet is a prime candidate for mobile transport networks (Xhaul), due to its flexibility, ubiquity, and cost-effectiveness. Understanding its performance under different network configurations would allow concluding about its appeal for Cloud-RAN. On the other hand, evaluating resource sharing mechanisms is relevant to put in place best solutions to host multiple virtual Base Band Units (vBBUs) into the same compute infrastructure. This paper assesses the feasibility of using a switched Ethernet Xhaul, by instantiating two vBBUs using different functional splits. Moreover, this paper evaluates two mechanisms for sharing network interface cards (NIC) in a general purpose server (GPS) hosting vBBUs. Our results point to a marginal performance degradation caused by the switched Ethernet Xhaul and the NIC sharing mechanisms. Such deviations could be seen from the increase in average and maximum Jitter and RTT results.

The paper investigates the evaluating task of the traffic as the registered number of vehicles of one of the three classes (a bus, passenger car or truck) that passed in a certain direction per unit of time, according to data from CCTV cameras in real time. For simplification this problem solving was divided into three components. They are registration of traffic flow objects and their classification, finding trajectories of fixed objects and determining traffic lanes, as well as counting objects in each direction. A comparative analysis of the existing algorithms, software and hardware systems that solve problems similar to the problems was carried out; also, a proprietary approach was proposed. The analysis describes the feasibility for developing their own approach due to the lack of an algorithm that meets all the requirements, such as estimating the traffic on the basis of data from surveillance cameras. Besides, the existing hardware and software systems are of the high cost and complexity. The YOLO artificial neural network was used to recognize objects on the frame in the form of rectangles containing the image of a vehicle. To build tracks, objects are compared frame-by-frame based on a set of characteristics, including a simple (average) perceptual hash and the coordinates of the corresponding rectangle. The developed algorithm for constructing trajectories of moving traffic objects, highlighting lanes of automobile traffic and counting vehicles is proposed as a software module. The testing results concerning the quality of the algorithm are introduced. The main advantages and disadvantages of the proposed approach are highlighted.

Digital image correlation (DIC) method is a rapid development of photomechanics technology. The basic principle of the method is calculated the correlation between before and after deformation of the specimen surface speckle images, which is used to determine displacement and deformation. DIC measurement system includes hardware and software system. The former is the speckle image acquisition system, the latter are speckle image analysis algorithm and implementation procedures. Because the software analysis algorithm can achieve sub-pixel accuracy or even more, most of scholars have focused on the speckle image analysis algorithms. The system performance caused by the composition of hardware system has been less introduced. The hardware system mainly included the camera, lenses, lighting and other components. If hardware system is not perfect and stable, it will bring hundreds or even thousands of micro strain measurement error. These unfavorable factors make 2D-DIC inaccurate in small deformation tests. To some extent, it limits the application of 2D-DIC in the engineering practice. This paper analyzed that the various components of DIC hardware system impacted on the system performance, It was given that how to reasonably select the various components in the typical cases, as well as involved that the selection of 2D-DIC measurement system is applied to the actual engineering measurements in high temperature environment. These can provide support that 2D-DIC measurement system is better applied to the engineering practice.

SPECjvm2008 is a new multi-threaded Java benchmark from SPEC and it replaces the aging single threaded SPECjvm98. The benchmark is intended to address several shortcomings of the earlier workloads in SPECjvm98 by replacing DB, Chart, Javac; removing Jess, adding XML, Serial, Crypto, in-cache and out-cache versions of Scimark workloads. It is targeted for measuring the performance of both JVM and hardware systems. In this paper we describe the salient features of SPECjvm2008. We then take a first look at the performance of this benchmark on current multi-core platforms and study the sensitivity of the components of the workload to basic architectural aspects such as the number of processor cores, the processor frequency, cache and memory sub-system. We focus our study on understanding how the behavior of this workload compares with other standard Java benchmarks, SPECjbb2005 and SPECjAppServer2004, both in components of the software stack that the workloads touch as well as in the aspects of the platform that they exercise and draw conclusion on the usefulness of SPECjvm2008 for practitioners of JVM and hardware performance analysis.KeywordsSPECJava PerformanceWorkload Characterization

High speed routers in Internet are becoming increasingly more powerful, as well as more energy hungry. However, they always show power-inefficient property due to we unilaterally in pursuit of high speed before. In response to this problem, we present a power-efficient router architecture named GreenRouter in this paper. GreenRouter separates a line card into two parts physically: the network interface card (named as DB) and the packet processing card (named as MB), which are interconnected by a two-stage unidirectional switch fabric. Traffic from all the DBs shares all the MBs in GreenRouter, thus the traffic can be aggregated to a few active MBs when traffic is light and the inactive MBs can be shut down to save power. We give the detailed architectural design of GreenRouter. Real-trace driven experiments show that GreenRouter can save about 50% power compared to the conventional router when the average traffic load is 30%, while providing quality of service guarantee at the same time.

After a deep analysis on how to use an image processing system to detect the missing holes on the motor carling, we design the whole system combined with the actual production conditions of the motor carling. Afterwards we explain the whole system's hardware and software in detail. We introduce the general functions for the system's hardware and software. Analyzed these general functions, we discuss the modules of the system's hardware and software and the theory to design these modules in detail. The measurement to confirm the area to image processing, edge detection, randomized Hough transform to circle detecting is explained in detail. Finally, the system result tested in the laboratory and in the factory is given out.

An integrated hardware and software system is used in studying neural correlates of learning. The hardware system is designed to maximize experimental flexibility, while the software system is designed to maximize computer speed for data acquisition and programmer efficiency for data analysis.

Autonomous underwater vehicles (AUVs) have many, scientific, military, and commercial applications because of their potential capabilities and significant cost-performance improvements. Typical AUV development requires critical system design and many costly at-sea trials during which systems specifications can be validated. Modeling and simulation provides a cost-effective method for carrying out preliminary component or system (hardware and software) testing and verification. Due to the complexity of most AUV development and their tight schedules, the simulated systems often differ considerably from the actual embedded architecture, thereby reducing the fidelity of the entire simulation. We adopted a hardware-in-the-loop (HIL) simulation approach that includes some level of the system's hardware and software. As expected, an HIL simulation requires all components be run under hard real-time constraint. The paper presents our implementation and considerations on HIL simulation for single and multiple vehicles. A brief mention of sensor and environment modeling is also provided.

Preventing malicious communication using virtualization

Voting is an important operation in multichannel computation paradigm and realization of ultrareliable and real-time control systems that arbitrates among the results of N redundant variants. These systems include N-modular redundant (NMR) hardware systems and diversely designed software systems based on N-version programming (NVP). Depending on the characteristics of the application and the type of selected voter, the voting algorithms can be implemented for either hardware or software systems. In this paper, a novel voting algorithm is introduced for real-time fault-tolerant control systems, appropriate for applications in which N is large. Then, its behavior has been software implemented in different scenarios of error-injection on the system inputs. The results of analyzed evaluations through plots and statistical computations have demonstrated that this novel algorithm does not have the limitations of some popular voting algorithms such as median and weighted; moreover, it is able to significantly increase the reliability and availability of the system in the best case to 2489.7% and 626.74%, respectively, and in the worst case to 3.84% and 1.55%, respectively.