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Operating system level trace analysis for automated problem identification

Open Cybernetics and Systemics Journal 2011年第1期5卷 45-52页

作者： Matni, Gabriel N. Dagenais, Michel R. Department of Computer and Software Engineering Ecole Polytechnique de Montreal C.P. 6079 Station Downtown Montreal QC H3C 3A7 Canada

Performance bottlenecks, malicious activities, programming bugs and other kinds of problematic behavior could be accurately detected on production systems if the relevant events were being monitored. This could be achieved through kernel level tracing where every time a relevant event occurs, the information is analysed or saved in a trace file to be inspected during post-mortem analysis. While collecting the information from the kernel has a very low impact, the offline analysis is typically performed remotely with no overhead on the system whatsoever. This article presents an automata-based approach for analyzing traces generated by the kernel of an operating system. Some typical patterns of problematic behavior are identified and described using the State Machine Language. These patterns are fed into an offline analyzer which efficiently and simultaneously checks for their occurrences even in traces of several gigabytes. The analyzer achieves a linear performance with respect to the trace size. The remaining factors impacting its performance are also discussed. The main interest of the proposed approach is the efficiency obtained in monitoring such extensive and detailed execution traces for a very large number of simultaneous possible patterns of problematic behavior. Copy;Matni and Dagenais.

关键词： Pattern matching

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Virtual systems tracing for performance analysis

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Open Cybernetics and Systemics Journal 2011年第1期5卷 1-15页

作者： Heidari, Parisa desnoyers, Mathieu Dagenais, Michel R. Department of Computer and Software Engineering Ecole Polytechnique de Montreal P.O. Box 6079 Succ. Downtown Montreal QC H3C 3A7 Canada

This paper describes extensions to the Linux Trace Toolkit next generation (LTTng), to trace the Xen hypervisor for efficiently tracing complete systems. LTTng is a low impact, modular, extensible, operating system tracer, while Xen is an hypervisor based on paravirtualization. Typically, one or several instances of Linux will run on top of the Xen hypervisor. The extended LTTng is able to trace all Linux instances and the hypervisor layer to give a global view of the system. An automated benchmark was created to measure the overhead imposed by tracing and Xen paravirtualization. It compares the performance of systems, with and without virtualization and tracing. The results obtained with different tests, using this procedure, are presented and show a negligible impact caused by tracing and a reasonable overhead caused by paravirtualization. Nonetheless, for some I/O intensive applications, the overhead imposed by paravirtualization is less negligible. © Heidari et al.

关键词： Virtualization

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UHF detection of PD in power transformers: The influence of disturbances

UHF detection of PD in power transformers: The influence of ...

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2011 Annual Report Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2011

作者： Cavallini, Andrea Ramos, Carlos Gustavo Azcarraga Montanari, Gian Carlo Saad, Hani Tozzi, Marco Dipartimento di Ingegneria Elettrica Universit di Bologna Viale Risorgimento 2 40136 Bologna Italy Ecole Polytechnique de Montreal Dept. of Electrical Engineering Montreal H3C 3A7 Canada TechImp HQ Srl Via Toscana 11 40069 Zola Predosa Italy

ISBN: (纸本)9781457709852

Ultra-high frequency partial discharge sensors are often deemed to be immune to disturbance, i.e., signals generated by partial discharge sources outside the transformer itself. In this paper, the above claim is investigated resorting to both computer simulations and experimental tests. The results indicate that corona from power lines in proximity of a transformer, or surface discharges on the surface of bushings can provide signals that are comparable with those generated by PD sources. These findings suggest that care must be taken when evaluating data coming from this type of sensors, as false alarms can be obtained. © 2011 IEEE.

关键词： Surface discharges

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An Empirical Study of the Impact of Two Antipatterns, Blob and Spaghetti Code, on Program Comprehension

An Empirical Study of the Impact of Two Antipatterns, Blob a...

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(CSMR) European Conference on software Maintenance and Reengineering

作者： Marwen Abbes Foutse Khomh Yann-Gaël Guéhéneuc Giuliano Antoniol Ptidej Team SOCCER LabDGIGL Ecole Polytechnique de Montreal Montreal Canada Ptidej Team SOCCER Lab DGIGL Canada Dépt. d'Informatique et de Recherche Opérationnelle Université de Montréal Montréal Canada Dept. of Elec. and Comp. Engineering Queen's University Kingston Ontario Canada

Antipatterns are "poor" solutions to recurring design problems which are conjectured in the literature to make object-oriented systems harder to maintain. However, little quantitative evidence exists to support this conjecture. We performed an empirical study to investigate whether the occurrence of antipatterns does indeed affect the understandability of systems by developers during comprehension and maintenance tasks. We designed and conducted three experiments, with 24 subjects each, to collect data on the performance of developers on basic tasks related to program comprehension and assessed the impact of two antipatterns and of their combinations: Blob and Spaghetti Code. We measured the developers' performance with: (1) the NASA task load index for their effort, (2) the time that they spent performing their tasks, and, (3) their percentages of correct answers. Collected data show that the occurrence of one antipattern does not significantly decrease developers' performance while the combination of two antipatterns impedes significantly developers. We conclude that developers can cope with one antipattern but that combinations of antipatterns should be avoided possibly through detection and refactorings.

关键词： Maintenance engineering Programming Analysis of variance Java Indexes NASA Time measurement

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Using a swarm of self-propelled natural microrobots in the form of flagellated bacteria to perform complex micro-assembly tasks

Using a swarm of self-propelled natural microrobots in the f...

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IEEE International Conference on Robotics and Automation (ICRA)

作者： Sylvain Martel Mahmood Mohammadi NanoRobotics Laboratory Department of Computer and Software Engineering the Institute of Biomedical Engineering Ecole Polytechnique de Montreal Montreal QUE Canada NanoRobotics Laboratory Ecole Polytechnique de Montreal Canada

ISBN: (纸本)9781424450381;9781424450404

Many science fiction novels have envisioned swarms of artificial microrobots capable of performing complex collective tasks. Unfortunately, today's technological constraints have prevented such powerful concept to be a reality when considering artificial microrobots. In this paper, we show that a swarm of computer-controlled flagellated Magnetotactic Bacteria (MTB) acting as natural microrobots of approximately 1 to 2 micrometers in diameter can perform many of the same complex collective tasks envisioned with these futuristic self-propelled artificial microrobots. To prove the concept, magnetotaxis-based control has been used to coordinate a swarm made of thousands of these self-propelled natural microrobots to build in a collective effort, a miniature version of an ancient Egyptian pyramid.

关键词： Microorganisms Propulsion Joining processes Nanoparticles Humans Micromotors Magnetic resonance imaging Microassembly Biomedical engineering Robotics and automation

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UHF deTECTION OF PD IN POWER TRANSFORMERS: THE INFLUENCE OF DISTURBANCES

UHF DETECTION OF PD IN POWER TRANSFORMERS: THE INFLUENCE OF ...

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Annual Report Conference on Electrical Insulation and Dielectric Phenomena

作者： Andrea Cavallini Carlos Gustavo Azcarraga Ramos Gian Carlo Montanari Hani Saad Marco Tozzi Dipartimento di Ingegneria Elettrica Università di Bologna Viale Risorgimento 2 40136 Bologna Italy Ecole Polytechnique de Montreal Dept. of Electrical Engineering Montreal Canada H3C 3A7 TechImp HQ Srl Via Toscana 11 40069 Zola Predosa Italy

ISBN: (纸本)9781457709852

关键词： deTECTION PD DISTURBANCES

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Identifying licensing of jar archives using a code-search approach

Identifying licensing of jar archives using a code-search ap...

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7th IEEE Working Conference on Mining software Repositories, MSR 2010, Co-located with the 2010 ACM/IEEE International Conference on software engineering, ICSE 2010

作者： Di Penta, Massimiliano German, Daniel M. Antoniol, Giuliano Dept of Engineering University of Sannio Italy Dept. of Computer Science University of Victoria Canada SOCCER Lab. DGIGL École Polytechnique de Montréal Montreal QC Canada

ISBN: (纸本)9781424468034

Free and open source software strongly promotes the reuse of source code. Some open source Java components/ libraries are distributed as jar archives only containing the bytecode and some additional information. For whoever wanting to integrate this jar in her own project, it is important to determine the license(s) of the code from which the jar archive was produced, as this affects the way that such component can be used. This paper proposes an automatic approach to determine the license of jar archives, combining the use of a code-search engine with the automatic classification of licenses contained in textual files enclosed in the jar. Results of an empirical study performed on 37 jars-from 17 different systems-indicate that this approach is able to successfully infer the jar licenses in over 95% of the cases, but that in many cases the license in textual files may differ from the one of the classes contained in the jar. © 2010 IEEE.

关键词： Open systems

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A novel failure recovery mechanism for GMPLS networks

A novel failure recovery mechanism for GMPLS networks

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2009 International Conference on High Performance Computing, Networking and Communication Systems, HPCNCS 2009

作者： Harhira, Hichem A. Pierre, Samuel Software and Computer Engineering Ecole Polytechnique de Montreal CP. 6079 Succ. Centre-Ville Montreal QC H3C 3A7 Canada

ISBN: (纸本)9781615676606

In next generation networks (NGNs), failure recovery is gaining more and more importance in high-capacity networks where IP and optical technologies have converged with a GMPLS-based control plane. This paper proposes a novel reactive failure recovery mechanism in GMPLS networks, which is based on formulating the problem as a Integer Linear Programming (ILP) model that reactively restores the set of broken-down LSPs following a simple or multiple link failure. In order to minimize the restoration delays, this mechanism first considers the topology (set of lightpaths) that is already in place before rerouting the LSPs. When no possible path is found, a new lightpath is set up dynamically, resulting in additional set-up signaling delays. Comparative simulation results confirm that our novel mechanism generates superior recovery levels especially as the network's load increases.

关键词： Next generation networks

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3D reconstruction of the human spine from radiograph(s) using a multi-body statistical model

3D reconstruction of the human spine from radiograph(s) usin...

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Medical Imaging 2009: Visualization, Image-Guided Procedures, and Modeling

作者： Jonathan, Boisvert Cheriet, Farida Pennec, Xavier Ayache, Nicholas School of Computing Queen's University Kingston ON Canada Dept. of Computer Engineering Ecole Polytechnique de Montreal Canada Asclepios Project Team INRIA Sophia Antipolis France

ISBN: (纸本)9780819475121

Three-dimensional models of the spine are very important in diagnosing, assessing, and studying spinal deformities. These models are generally computed using multi-planar radiography, since it minimizes the radiation dose delivered to patients and allows them to assume a natural standing position during image acquisition. However, conventional reconstruction methods require at a minimum two sufficiently distant radiographs (e.g., posterioranterior and lateral radiographs) to compute a satisfactory model. Still, it is possible to expand the applicability of 3D reconstructions by using a statistical model of the entire spine shape. In this paper, we describe a reconstruction method that takes advantage of a multi-body statistical model to reconstruct 3D spine models. This method can be applied to reconstruct a 3D model from any number of radiographs and can also integrate prior knowledge about spine length or preexisting vertebral models. Radiographs obtained from a group of 37 scoliotic patients were used to validate the proposed reconstruction method using a single posterior-anterior radiograph. Moreover, we present simulation results where 3D reconstructions obtained from two radiographs using the proposed method and using the direct linear transform method are compared. Results indicate that it is possible to reconstruct 3D spine models from a single radiograph, and that its accuracy is improved by the addition of constraints, such as a prior knowledge of spine length or of the vertebral anatomy. Results also indicate that the proposed method can improve the accuracy of 3D spine models computed from two radiographs. © 2009 SPIE.

关键词： Image reconstruction

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Dynamic admission control and path allocation for SLAs in DiffServ networks

Dynamic admission control and path allocation for SLAs in Di...

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Canadian Conference on Electrical and computer engineering (CCECE)

作者： Hichem Ayed Harhira Samuel Pierre Department of Software and Computer Engineering Ecole Polytechnique de Montreal Montreal Canada

Today's converged networks are mainly characterized by their support of real-time and high priority traffic requiring a certain level of quality of service (QoS). In this context, traffic classification and prioritization are key features in providing preferential treatments of the traffic in the core of the network. In this paper, we address the joint problem of path allocation and admission control (JPAC) of new Service Level Agreements (SLA) in a DiffServ domain. In order to maximize the resources utilization and the number of admitted SLAs in the network, we consider a statistical bandwidth constraints allowing for a certain overbooking over the network's links. SLAs' admissibility decisions are based on solving to optimality an integer linear programming (ILP) model. When tested by simulations, numerical results confirm that the proposed model can be solved to optimality for real-sized instances within acceptable computation times and substantially reduces the SLAs blocking probability, compared to a the Greedy mechanism proposed in the literature.

关键词： Admission control Quality of service Diffserv networks Telecommunication traffic Communication system traffic control Bandwidth Resource management Probes software quality computer networks

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