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Moret P.,University of Lugano | Binder W.,University of Lugano | Villazon A.,Bolivian Private University, Cochabamba | Ansaloni D.,University of Lugano | Heydarnoori A.,University of Lugano
Software - Practice and Experience | Year: 2010

Calling context profiling is an important technique for analyzing the performance of object-oriented software with complex inter-procedural control flow. The Calling Context Tree (CCT) is a common data structure that stores dynamic metrics, such as CPU time, separately for each calling context. As CCTs may comprise millions of nodes, there is a need for a condensed visualization that eases the localization of performance bottlenecks. In this article, we discuss Calling Context Ring Charts (CCRCs), a compact visualization for CCTs, where callee methods are represented in ring segments surrounding the caller's ring segment. In order to reveal hot methods, their callers, and callees, the ring segments can be sized according to a chosen dynamic metric. We describe two case studies where CCRCs help us to detect and fix performance problems in applications. A performance evaluation also confirms that our implementation can efficiently handle large CCTs. Copyright © 2010 John Wiley & Sons, Ltd.

Schoeberl M.,Technical University of Denmark | Binder W.,University of Lugano | Villazon A.,Bolivian Private University, Cochabamba
Proceedings - 2011 14th IEEE International Symposium on Object/Component/Service-Oriented Real-Time Distributed Computing, ISORC 2011 | Year: 2011

To avoid data cache trashing between heap-allocated data and other data areas, a distinct object cache has been proposed for embedded real-time Java processors. This object cache uses high associativity in order to statically track different object pointers for worst-case execution-time analysis. However, before implementing such an object cache, an empirical analysis of different organization forms is needed. We use a cross-profiling technique based on aspect-oriented programming in order to evaluate different object cache organizations with standard Java benchmarks. From the evaluation we conclude that field access exhibits some temporal locality, but almost no spatial locality. Therefore, filling long cache lines on a miss just introduces a high miss penalty without increasing the hit rate enough to make up for the increased miss penalty. For an object cache, it is more efficient to fill individual words within the cache line on a miss. © 2011 IEEE.

Villazon A.,University of Lugano | Villazon A.,Bolivian Private University, Cochabamba | Binder W.,University of Lugano | Moret P.,University of Lugano | Ansaloni D.,University of Lugano
Science of Computer Programming | Year: 2011

Aspect-oriented programming (AOP) has been successfully applied to application code thanks to techniques such as Java bytecode instrumentation. Unfortunately, with existing AOP frameworks for Java such as AspectJ, aspects cannot be woven into the standard Java class library. This restriction is particularly unfortunate for aspects that would benefit from comprehensive aspect weaving with complete method coverage, such as profiling or debugging aspects. In this article we present MAJOR, a new tool for comprehensive aspect weaving, which ensures that aspects are woven into all classes loaded in a Java Virtual Machine, including those in the standard Java class library. MAJOR includes the pluggable module CARAJillo, which supports efficient access to a complete and customizable calling context representation. We validate our approach with three case studies. Firstly, we weave existing profiling aspects with MAJOR which otherwise would generate incomplete profiles. Secondly, we introduce an aspect for memory leak detection that also benefits from comprehensive weaving. Thirdly, we present an aspect subsuming the functionality of ReCrash, an existing tool based on low-level bytecode instrumentation techniques that generates unit tests to reproduce program failures. Our aspect-based tools are concisely implemented in a few lines of code, and leverage MAJOR and CARAJillo for comprehensive aspect weaving and for efficient access to calling context information. © 2011 Elsevier B.V. All rights reserved.

Palacios-Marques D.,Polytechnic University of Valencia | Saldana A.Z.,Bolivian Private University, Cochabamba | Vila J.E.,University of Valencia
Kybernetes | Year: 2013

Purpose: Firms are adopting Web 2.0 technologies to improve collaboration, participation and communication; however there are few empirical studies testing the impact of this adoption. The purpose of this article is to analyze if there is a linkage amongst market orientation, Web 2.0 adoption and innovativeness. Design/methodology/approach: Structural equation modeling was used to test the relationships amongst the variables. A sample of 244 firms of the hospitality industry was used. The theoretical approach is based on the market orientation and innovativeness, concepts, which have been studied by various authors in the literature. Findings: A positive relationship was found between market orientation and Web 2.0 adoption and between Web 2.0 adoption and innovativeness. Research limitations/implications: The study was developed in one industry, so in order to generalize the findings, additional testing in other industries should be developed. In addition a longitudinal study is encouraged. Practical implications: Managers are advised to adopt Web 2.0 technologies to strengthen market orientation behaviors and innovativeness. Originality/value: This article empirically tested the relationship between market orientation and Web 2.0 adoption and the impact of Web 2.0 adoption on innovativeness. Although some managers and researchers have reported some positive impacts of Web 2.0 on different aspects of the organization, there are still few empirical studies, and the authors contributed to fill this void. © Emerald Group Publishing Limited.

Bell K.R.W.,University of Strathclyde | Nedic D.P.,Siemens AG | Salinas San Martin L.A.,Bolivian Private University, Cochabamba
IEEE Transactions on Sustainable Energy | Year: 2012

This paper describes a study conducted to address the question of how much power transfer capacity should be provided on a meshed transmission system to maintain reliability of supply to consumers in the presence of wind generation. A simulation methodology is presented that includes modeling of the available wind generation in the longer term across a quite large area taking into account correlations in available power between different locations in that area. A description is given of the results obtained in characterization of the relationship between the peak load in an area, the total generation capacity in that area, the proportion of it that is wind generation, and how much transmission import capability - "interconnection reserve" - is required for a given reliability of supply. Finally, a number of issues faced by power system investment planners are discussed and pointers given to further work to enable transmission utilities to meet the challenges presented by policy makers in respect of development of wind power to meet renewable energy targets. © 2010-2012 IEEE.

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