Murray Woodside

Enhanced Modeling and Solution of Layered Queueing Networks

Layered queues are a canonical form of extended queueing network for systems with nested multiple resource possession, in which successive depths of nesting define the layers. The model has been applied to most modern distributed systems, which use different kinds of client-server and master-slave relationships, and scales up well. The layered queueing network (LQN) model is described here in a unified fashion, including its many more extensions to match the semantics of sophisticated practical distributed and parallel systems. These include efficient representation of replicated services, parallel and quorum execution, and dependability analysis under failure and reconfiguration. The full LQN model is defined here and its solver is described. A substantial case study to an air traffic control system shows errors (compared to simulation) of a few percent. The LQN model is compared to other models and solutions, and is shown to cover all their features.

Performance model driven QoS guarantees and optimization in clouds

This paper presents a method for achieving optimization in clouds by using performance models in the development, deployment and operations of the applications running in the cloud. We show the architecture of the cloud, the services offered by the cloud to support optimization and the methodology used by developers to enable runtime optimization of the clouds. An optimization algorithm is presented which accommodates different goals, different scopes and timescales of optimization actions, and different control algorithms. The optimization here maximizes profits in the cloud constrained by QoS and SLAs across a large variety of workloads.

Annotating UML models with non-functional properties for quantitative analysis

This work is motivated by the recent Request For Proposals issued by OMG for a new UML Profile named “Modeling and Analysis of Real-Time and Embedded systems”. The paper describes first some domain concepts for annotating Non-Functional Properties (NFPs), whose focus is on supporting temporal verification of UML-based models. Particular emphasis is given to schedulability and performance analysis for real-time systems. We discuss next some general requirements for NFP annotations and evaluate how the UML profiles for “Schedulability, Performance, and Time Specification” and for “Modeling Quality of Service and Fault Tolerance Characteristics and Mechanisms”, address these requirements. Last but not least, the paper proposes a preliminary framework for describing NFPs by considering the major requirements previously stated and by analyzing some UML mechanisms to attach NFPs to model elements.

Automated performance modeling of softwaree genrated by a design environment

Abstract Automation is needed to make performance modeling faster and more accessible to software designers. This paper describes a prototype tool that exploits recently developed techniques for automatic model construction from traces. The performance model is a layered queuing model and it is based on traces captured for certain selected scenarios which are determined to be important for performance. The prototype tool has been integrated with a commercial software design environment that generates code with heavy use of standard libraries. The execution costs of the libraries has also been captured and used in the automatic model creation. The approach not only automates building early models, but also gives models which can be maintained during development, using traces gathered from the implementations. The paper describes the tool, the process by which it is applied, the process of capturing and managing the execution cost data, and an example. To use the tool, the designer further defines the scenarios, the execution environment, and the workload intensity parameters. The designer can then experiment with different environments and workloads, or revise the design, to improve the performance.

On the effect of traffic model to the performance evaluation of multicast protocols in MANET

While efforts have been made recently to evaluate the performance of multicasting protocols in mobile ad hoc networks (MANET) and to evaluate the capacity of ad hoc networks, very little is understood or known about the traffic characteristics of mobile ad hoc networks and its effect on the performance of the existing multicasting protocols. In this paper, traffic models for multicast protocols in MANET are outlined. A literature survey for multicast protocols in MANET is conducted. Classification for most MANET multicast protocols is presented. A research to evaluate the performance of the existing multicast protocols in MANET using self-similarity traffic model is proposed & justified

Challenges in Automating Performance Tool Support

Research and development (R&D) of new tools for performance analysis faces many challenges from immaturity and lack of documentation of supporting tools and infrastructure, incompatibility of tools, lack of access to realistic case studies and performance parameters for them, validation of results, time required versus benefit of results, subsequent maintenance, and many, many others. Yet tool development is an essential part of practical R&D. The panelists relay experiences in developing tools, discuss what needs improvement, opportunities in developing R&D tools, and offer advice for researchers. After introductory remarks from each panelist, there will be a discussion session with the audience.