Performance And Reliability Analysis Of Computer Systems (an Example-based Approach Using The Sharpe Software

Computation of bounds for transient measures of large rewarded Markov models using regenerative randomization

Performance and Reliability Analysis of Computer Systems

Time analysis is a common approach for testing and detecting methods for the performance analysis of computer systems. In the article it is shown, that measuring and identifying performances based on a benchmark is not sucient for the proper analysis of the computer systems behavior. The response time of the process is often composed of the execution of many subprocesses or many paths of execution. Under this assumption, it is presented, that both convolution and deconvolution methods can be helpful in obtaining time distributions and modeling of complex processes. In such a modeling the analysis of measurement errors is very important and was taken into consideration. The example of using the methods in buering process is also discussed.

The First International Workshop on Teaching Performance Analysis of Computer Systems (TeaPACS1) in 2021 came to the conclusion among participants that there is a need to continue and regularly update the discussion on teaching strategies, changing the curriculum, reaching out to the systems community, facing the new generation and their new learning habits, etc.

Mean Value Analysis (MVA) has long been a standard approach for performance analysis of computer systems. While the exact load-dependent MVA algorithm is an efficient technique for computer system performance modeling, it fails to address several features of multi-core platforms. In addition, the load-dependent MVA algorithm suffers from numerical difficulties under heavy load conditions. The goal of our paper is to find an efficient and robust method which is easy to use in practice and also achieves accuracy for performance prediction for multi-core platforms. Our contributions are: We present a flow-equivalent performance model designed specifically to address multi-core computer systems. We identify the influence on the CPU demand of the effects of Dynamic Frequency Scaling (DFS) and Hyper-Threading Technology (HTT). We adopt an approximation technique to estimate resource demands to parameterize the MVA algorithm. We use a modified Conditional MVA (CMVA) algorithm to address the potential numerical instability. To validate the application of our method, we investigate a case study of an e-commerce web server which is equipped with diverse classes of user requests. We show that our method achieves better accuracy compared with other commonly used MVA algorithms.

This paper assesses the state of the art in cost-benefit analyses of computer graphics systems and suggests an approach for developing improved methodology. Cost-benefit analyses are distinguished from analyses of system performance in that the latter is directed at optimizing system performance at a given level of investment, while the former is directed at justifying the investment itself.Computer graphic system design alternatives are first outlined. Then methods of analyzing the performance and costs of computer systems in general and graphic systems in particular are discussed. With this information it is shown how cost-effectiveness analyses may be performed. The next crucial step is to conduct benefit analysis, an ill-defined art. The results of benefit analysis must be combined with cost-effectiveness analysis in order to perform the desired cost-benefit analysis.An experimental methodology is suggested for better performing benefit analyses of computer graphics systems. A more rigorous formulation of the cost-benefit procedure is then outlined. No attempt is made in this report to actually perform such an analysis.

User-controlled optimization of task scheduling for imprecise computer systems

In this paper we analyze the performance of a mobile edge computing (MEC) system in the presence of spatially correlated shadowing. To achieve this goal, obstacles like walls are modelled by a Manhattan Poisson line Process (MPLP). Simultaneous wireless information and power transfer (SWIPT) is used to send command messages as well as to deliver the power to low power devices (LPDs). The energy harvested by the LPDs in the downlink phase is then used to either locally execute the assigned computation task or to offload it to the MEC server. By leveraging stochastic geometry, we derive analytical expressions for the success probability of the system which is defined as the joint probability of SINR downlink coverage and of harvesting enough energy to execute the computation task. Moreover, the impact of different system parameters on the trade-off between the harvested energy and the computational task admission rate is analyzed.

Ring resonators are used as photon pair sources by taking advantage of the materials second or third order non- linearities through the processes of spontaneous parametric downconversion and spontaneous four wave mixing respectively. Two materials of interest for these applications are silicon for the infrared and aluminum nitride for the ultraviolet through the infrared. When fabricated into ring type sources they are capable of producing pairs of indistinguishable photons but typically suffer from an effective 50% loss. By slightly decoupling the input waveguide from the ring, the drop port coincidence ratio can be significantly increased with the trade-off being that the pump is less efficiently coupled into the ring. Ring resonators with this design have been demonstrated having coincidence ratios of 96% but requiring a factor of ~10 increase in the pump power. Through the modification of the coupling design that relies on additional spectral dependence, it is possible to achieve similar coincidence ratios without the increased pumping requirement. This can be achieved by coupling the input waveguide to the ring multiple times, thus creating a Mach-Zehnder interferometer. This coupler design can be used on both sides of the ring resonator so that resonances supported by one of the couplers are suppressed by the other. This is the ideal configuration for a photon-pair source as it can only support the pump photons at the input side while only allowing the generated photons to leave through the output side. Recently, this device has been realized with preliminary results exhibiting the desired spectral dependence and with a coincidence ratio as high as ~ 97% while allowing the pump to be nearly critically coupled to the ring. The demonstrated near unity coincidence ratio infers a near maximal heralding efficiency from the fabricated device. This device has the potential to greatly improve the scalability and performance of quantum computing and communication systems.

This report compares the performance of different computer systems in solving dense systems of linear equations. The comparison involves approximately a hundred computers, ranging from a CRAY Y-MP to scientific workstations such as the Apollo and Sun to IBM PCs.

This report compares the performance of different computer systems in solving dense systems of linear equations. The comparison involves approximately a hundred computers, ranging from a CRAY Y-MP to scientific workstations such as the Apollo and Sun to IBM PCs.

Trace-driven simulation is an important aid in performance analysis of computer systems. Capturing address traces for these simulations is a difficult problem for single processors and particularly for multicomputers. Even when existing trace methods can be used on multicomputers, the amount of collected data typically grows with the number of processors, so I/O and trace storage costs increase. A new technique is presented in this paper which modifies the executable code to dynamically collect the address trace from the user code and analyzes this trace during the execution of the program. This method helps resolve the I/O and storage problems and facilitates parallel analysis of the address trace. If a trace stored on disk is desired, the generated trace information can also be written to files during execution, with a resultant drop in program execution speed. An initial implementation on the Intel iPSC/2 hypercube multicomputer is detailed, and sample simulation results are presented. The effect of this trace collection method on execution time is illustrated.

The paper highlights the reliability estimation tool for power system's reliability estimation study. The reliability estimation tool was applied to the different configurations of Uninterruptible Power Supply (UPS) systems Capacity, Isolated Redundant, Parallel Redundant, Distributed Redundant, and System plus System Redundant configurations. UPS reliability parameters such as failure rates, Mean Time Between Failures, and Availability can be estimated from the proposed system's reliability estimation methods. The suggested reliability estimation methods in this paper are the Reliability Block Diagram (RBD) and the Monte-Carlo simulation methods. The UPS system reliability estimation study found that the System plus System Redundant configuration gives the highest reliability and availability values compared to all other configurations. Studies has been conducted to investigate the effects of the reliability level of every component in the UPS system onto the overall system's reliability, thus making it possible to rank their contribution to system's reliability and thereby useful in establishing the area of improvement in the design of the highest UPS system's reliability.

Reliability and availability analysis of dependent–dynamic systems with DRBDs

The performance of computer systems can in theory be optimized by selecting the system configuration having the best simulated performance. Unfortunately, it is often computationally intractable to estimate the performance of all system configurations accurately via simulation. We propose an algorithm for finding the best system configuration without estimating the performance of each system configuration accurately, so that the total simulation time is minimized. We prove that with high probability our algorithm finds the best system configuration. In addition, our algorithm has an advantage in that it only infrequently changes the system configurations to be simulated. Numerical experiments show that our algorithm improves upon existing algorithms with respect to the total simulation time and the frequency of changing the system configurations.