Christopher X. Brooks

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We describe a methodology that enables the real-time diagnosis of performance problems in complex high-performance distributed systems. The methodology includes tools for generating precision event logs that can be used to provide detailed end-to-end application and system level monitoring; a Java agent-based system for managing the large amount of logging(More)
Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to(More)
Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to(More)
We study the simultaneous use of multiple modeling techniques in the design of embedded systems. We begin with a pre-existing Statecharts model of a simple case study, a traffic light for a pedestrian crossing, using it to illustrate the need for multimodeling and the pitfalls. The original model combines two distinct models of computation (MoCs), finite(More)
In this paper, we explain how to achieve deterministic execution of FMUs (Functional Mockup Units) under the FMI (Functional Mockup Interface) standard. In particular, we focus on co-simulation, where an FMU either contains its own internal simulation algorithm or serves as a gateway to a simulation tool. We give conditions on the design of FMUs and master(More)
A model of computation (MoC) is a formal abstraction of execution in a computer. There is a need for composing MoCs in e-science. Kepler, which is based on Ptolemy II, is a scientific workflow environment that allows for MoC composition. This paper explains how MoCs are combined in Kepler and Ptolemy II and analyzes which combinations of MoCs are currently(More)
1. With contributions from the entire Ptolemy II team. 2. The version number for VisualSense matches the version of Ptolemy II on which it is based. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute the VisualSense software and its documentation for any purpose, provided that(More)
a r t i c l e i n f o a b s t r a c t Scientific applications, often expressed as workflows are making use of large-scale national cyberinfrastructure to explore the behavior of systems, search for phenomena in large-scale data, and to conduct many other scientific endeavors. As the complexity of the systems being studied grows and as the data set sizes(More)