This tutorial will provide insight into the causes of the discrepancy between the raw transmission rate of physical media and the throughput rates observed by the end user. Some of the specific light-weight protocols ...
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This tutorial will provide insight into the causes of the discrepancy between the raw transmission rate of physical media and the throughput rates observed by the end user. Some of the specific light-weight protocols that are currently being developed for the network and transport layers of the OSI model will be examined. Finally, other measures of network performance, such as latency, which may actually be more important than throughput for real-time applications, will be discussed.
The author introduces a new method of ensemble averaging in performance analysis. This method is based on analogies to the formalism of Gibbs ensemble theory. The method forms the basis of a unified computational proc...
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The author introduces a new method of ensemble averaging in performance analysis. This method is based on analogies to the formalism of Gibbs ensemble theory. The method forms the basis of a unified computational procedure to compute system performance measures for different models. It suggests a framework to assess the accuracy, to develop a 'second' order improvement approximation, and to show that under appropriate conditions, analogous to those in the thermodynamic limit, the approximations obtained are asymptotically exact.
The author considers the Threshold Fastest Emptying policy. In the context of a system with saturated readers the TFE policy specifies: Serve M readers utilizing all processors until the queue for writers reaches some...
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The author considers the Threshold Fastest Emptying policy. In the context of a system with saturated readers the TFE policy specifies: Serve M readers utilizing all processors until the queue for writers reaches some threshold K. Empty the system from readers as quickly as possible by finishing serving the active readers (a non-preemptive policy). Then serve all available writers. The cycle repeats.
A class of stochastic Petri nets with product form solution for the equilibrium state probabilities was described by A.A. Lazar and T.G. Robertazzi. For this class the Petri network consists of a number of linear sequ...
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A class of stochastic Petri nets with product form solution for the equilibrium state probabilities was described by A.A. Lazar and T.G. Robertazzi. For this class the Petri network consists of a number of linear sequences of places or subtasks with a vector of coordinates indicating which places are active. This work extends this class to the case where service times consist of a series of distinct exponential stages. Illustrative examples are given.
This paper provides a simple unifying framework and concrete condition in order to conclude product forms results for interconnection or broadcasting protocol structures such as CSMA. Generally, such structures are re...
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This paper provides a simple unifying framework and concrete condition in order to conclude product forms results for interconnection or broadcasting protocol structures such as CSMA. Generally, such structures are referred to as random access schemes as scheduled transmissions can be blocked based upon the random state of the system, representing idle and busy transmitters or links. The actual access protocol is crucial for explicit expressions of the steady state distribution.
The design of a hybrid measurement tool (LTRAMS) for a loosely-coupled multiprocessor (hypercube) is based on a previous design of a hybrid tool (TRAMS) which acquires event trace measurements on a tightly coupled sha...
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The design of a hybrid measurement tool (LTRAMS) for a loosely-coupled multiprocessor (hypercube) is based on a previous design of a hybrid tool (TRAMS) which acquires event trace measurements on a tightly coupled shared-memory MIMD architecture. A number of issues must be considered when applying this type of measurement tool to loosely-coupled, distributed-memory machines because of their architectural differences. These issues include synchronization and centralized vs. distributed functions. The LTRAMS triggering is done in software, while most of the measurement data sampling is done in hardware.
Markov models are widely used for the analysis of availability of computer/communication systems. Realistic models often involve state space cardinalities that are so large that it is impractical to generate the trans...
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Markov models are widely used for the analysis of availability of computer/communication systems. Realistic models often involve state space cardinalities that are so large that it is impractical to generate the transition rate matrix let alone solve for availability measures. Various state space reduction methods have been developed, particularly for transient analysis. In this paper we present an approximation technique for determining steady state availability. Of particular interest is that the method also provides bounds on the error. Examples are given to illustrate the method.
This tutorial will provide an overview of some problems and the state of the art on experimental methods in reliability measurement. Comparisons between the experiment and the real will be followed by identifying meas...
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This tutorial will provide an overview of some problems and the state of the art on experimental methods in reliability measurement. Comparisons between the experiment and the real will be followed by identifying measurements possible only through experiments. A few key experimental techniques will be introduced, followed by case studies for illustration. A technique useful to drive an experiment towards making certain empirical lower/upper bound measurements will be discussed. Such results are particularly useful for modeling and analysis. This will be followed by examples of experiments used to identify cause-effect relationships of earlier unexplained phenomenon. This tutorial is aimed at providing a background for the design of experiments and a bibliography to pursue further interest.
The response time is the most visible performance index to users of computersystems. End-users see individual response times, not the average. Therefore the distribution of response times is important in performance ...
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The response time is the most visible performance index to users of computersystems. End-users see individual response times, not the average. Therefore the distribution of response times is important in performance evaluation and capacity planning studies. However, the analytic results cannot be obtained in practical cases. A new queueing method is proposed to approximate the response-time distribution. Unlike the previous methods the proposed one takes into account the service-time distributions and routing behaviour. The reported results indicate that the method provides reasonable approximations in many cases.
This tutorial will address a performance prediction modeling paradigm and the practical concerns that arise from its application. A series of progressively refined and related real-world case studies will be given and...
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This tutorial will address a performance prediction modeling paradigm and the practical concerns that arise from its application. A series of progressively refined and related real-world case studies will be given and analyzed. These case studies span predictions for adding processors, balancing the load placed on storage devices, increasing the offered workload, selecting appropriate swapping devices, and partitioning binary n-cube architectures. A series of sensitivity analysis studies, both theoretical and experimental, will be presented. These studies build intuition regarding which modeling parameters are the most important and which must be modeled carefully. These studies also address parameter inter-dependency issues. Calibration techniques will be presented and compared, using both theoretical and real world examples.
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