Performance of multi-level client-server systems with parallel service operations

Abstract

l'arcrllel extcufzon can enhance the performance of dzsfrzhufed claen,f-server systems, but the enhancement ma,y he less than expected.Evaluatzons of such deszgns must rn,clude the complex eflects of overheads, heterogeneous parallel branch,es, contention by the parallel parts for servers in lower levels, and simultaneous resource possession effects. A "compensated complelnentary delay" approximation is described which explozis layered queuean,g approEzmations for layered re-.sources tuhach occur in client-server architectures, based on synchronazation dela,y estimates and adjusted levels of conieniion.The new approximataon uses the overlap of parallel branches and a new fast calculation of join drlalys. II gives acceptable errors (averaging about two percent), and has an enormously lower computational cost compared to the competang approach based on decompositzon.The new approximation may moderate a concluszon made by Heidelberger and Trivedi, that decomposition gives greatly superior accuracy to the much cheaper complementary delay approach; these delay approximations are only a little less accurate.

Performance modeling from software components

“…It can accept requests from entries or send requests to entries. The details of modeling with activities can be found in paper [7]. In LQN models, both nested components, and components giving the required services, are in lower layers (layers are a control hierarchy rather than a structure hierarchy).…”

Performance of Client/Server Systems

“…Performance can be potentially improved if a server can break down the execution of its tasks into parallel tasks that execute in parallel in a fork-and-join type of model. The evaluation of the performance gains of parallel servers must consider the effects of the overhead, and the contention for underlying resources [3].…”

Performance Modeling of a Service Provisioning Design

“…To study the system we develop a Layered Queuing Model (LQM) [4], [8], [7], [10]. LQMs describe the request scenarios submitted to a system and the resources they consume.…”