Thesis (M.S.)--Mississippi State University. Department of Computer Science. / Title from title screen. Includes bibliographical references.

Thesis (M.S.)--University of Texas at El Paso, 2008. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (doctoral)--University of Tartu, 2006. / Includes bibliographical references.

Several algorithms have been proposed to implement intrusion detection systems (IDS) based on the idea that anomalies in the behavior of a system might be produced by a set of actions of an intruder or by a system fault. Almost no previous research has been conducted in the area of anomaly detection for high performance clusters. The research reported in this thesis demonstrates that the analysis of sequences of function calls issued by one or more processes can be used to verify the correct execution of parallel programs written in C/C++ with the Message Passing Interface (MPI) in a cluster of Linux workstations. The functions calls were collected via library interposition. Two anomaly detection algorithms previously reported to be effective methods for anomaly detection in sequences of system calls, Hidden Markov Model and sequence matching, were implemented and tested. In general, the simpler sequence matching algorithm out-performed the Hidden Markov Model.

No description available.

This dissertation proposes the Weaves runtime framework for the execution of large scale parallel programs over lightweight intra-process threads. The goal of the Weaves framework is to help process-based legacy parallel programs exploit the scalability of threads without any modifications. The framework separates global variables used by identical, but independent, threads of legacy parallel programs without resorting to thread-based re-programming. At the same time, it also facilitates low-overhead collaboration among threads of a legacy parallel program through multi-granular selective sharing of global variables. Applications that follow the tenets of the Weaves framework can load multiple identical, but independent, copies of arbitrary object files within a single process. They can compose the runtime images of these object files in graph-like ways and run intra-process threads through them to realize various degrees of multi-granular selective sharing or separation of global variables among the threads. Using direct runtime control over the resolution of individual references to functions and variables, they can also manipulate program composition at fine granularities. Most importantly, the Weaves framework does not entail any modifications to either the source codes or the native codes of the object files. The framework is completely transparent. Results from experiments with a real-world process-based parallel application show that the framework can correctly execute a thousand parallel threads containing non-threadsafe global variables on a single machine - nearly twice as many as the traditional process-based approach can - without any code modifications. On increasing the number of machines, the application experiences super-linear speedup, which illustrates scalability. Results from another similar application, chosen from a different software area to emphasize the breadth of this research, show that the framework's facilities for low-overhead collaboration among parallel threads allows for significantly greater scales of achievable parallelism than technologies for inter-process collaboration allow. Ultimately, larger scales of parallelism enable more accurate software modeling of real-world parallel systems, such as computer networks and multi-physics natural phenomena. / Ph. D.

WEb Services constituem uma tecnologia emergente utilizada para disponibilização de serviços na Web. Devido aos complexos processos de negócio existentes, esses serviços são combinados para que operem seguindo um fluxo de trabalho. Esse processo é chamado de composição de Web Services. Como no processo de desenvolvimento de um software tradicional, a atividade de teste é fundamental no processo de desenvolvimento da composição de Web Services. Neste trabalho é proposta uma estratégia de teste para a composição de Web Services, em que especificações de composições são transformadas para um modelo de teste de programas paralelos baseados em passagem de mensagens. É proposto o conceito de grupos de elementos requeridos para melhorar a cobertura dos critérios. Uma ferramenta de apoio à estratégia de teste foi desenvolvida. Alguns estudos experimentais para avaliar a aplicabilidade da estratégia proposta também são apresentados. Além disso, é proposto um método que utiliza redes de Petri para eliminar sincronizações não-executáveis no envio e recebimento de mensagens / WEb Services constitute an emerging technology for deploying services in the Web. Due to the complex business processes, these services are combined to operate, following a workflow. This process is named Web Services Composition. As in the development process of a traditional software, the testing activity is fundamental in the development process of Web Services Composition. This work proposes a test strategy for Web Services Composition, in that composition specifications are transformed into a test model of message-passing parallel programs. The concept of required elements groups is proposed to improve the criteria coverage. A tool that supports the test strategy was developed. Some experimental studies for evaluating the applicability of proposed strategy are also presented. Furthermore, it presents a method that uses Petri Nets to eliminate non-executable synchronizations in the sending and receiving of messages

All market-leading processor vendors have started to pursue multicore processors as an alternative to high-frequency single-core processors for better energy and power efficiency. This transition to multicore processors no longer provides the free performance gain enabled by increased clock frequency for programmers. Parallelization of existing serial programs has become the most powerful approach to improving application performance. Not surprisingly, parallel programming is still extremely difficult for many programmers mainly because thinking in parallel is simply beyond the human perception. However, we believe that software tools based on advanced analyses can significantly reduce this parallelization burden. Much active research and many tools exist for already parallelized programs such as finding concurrency bugs. Instead we focus on program analysis algorithms that assist the actual parallelization steps: (1) finding parallelization candidates, (2) understanding the parallelizability and profits of the candidates, and (3) writing parallel code. A few commercial tools are introduced for these steps. A number of researchers have proposed various methodologies and techniques to assist parallelization. However, many weaknesses and limitations still exist. In order to assist the parallelization steps more effectively and efficiently, this dissertation proposes Prospector, which consists of several new and enhanced program analysis algorithms. First, an efficient loop profiling algorithm is implemented. Frequently executed loop can be candidates for profitable parallelization targets. The detailed execution profiling for loops provides a guide for selecting initial parallelization targets. Second, an efficient and rich data-dependence profiling algorithm is presented. Data dependence is the most essential factor that determines parallelizability. Prospector exploits dynamic data-dependence profiling, which is an alternative and complementary approach to traditional static-only analyses. However, even state-of-the-art dynamic dependence analysis algorithms can only successfully profile a program with a small memory footprint. Prospector introduces an efficient data-dependence profiling algorithm to support large programs and inputs as well as provides highly detailed profiling information. Third, a new speedup prediction algorithm is proposed. Although the loop profiling can give a qualitative estimate of the expected profit, obtaining accurate speedup estimates needs more sophisticated analysis. Prospector introduces a new dynamic emulation method to predict parallel speedups from annotated serial code. Prospector also provides a memory performance model to predict speedup saturation due to increased memory traffic. Compared to the latest related work, Prospector significantly improves both prediction accuracy and coverage. Finally, Prospector provides algorithms that extract hidden parallelism and advice on writing parallel code. We present a number of case studies how Prospector assists manual parallelization in particular cases including privatization, reduction, mutex, and pipelining.

Within the last decade multi-core processors have become increasingly commonplace with the power and performance demands of modern real-world programs acting to accelerate this trend. The rapid advancements in designing and adoption of such architectures mean that there is a serious need for programming models that allow the development of correct parallel programs that execute efficiently on these processors. A principle problem in this regard is that of efficiently synchronizing concurrent accesses to shared memory. Traditional solutions to this problem are either inefficient but provide programmability (coarse-grained locks) or are efficient but are not composable and very hard to program and verify (fine-grained locks). Optimistic Transactional Memory systems provide many of the composability and programmabillity advantages of coarse-grained locks and good theoretical scaling but several studies have found that their performance in practice for many programs remains quite poor primarily because of the high overheads of providing safe optimism. Moreover current transactional memory models remain rigid - they are not suited for expressing some of the complex thread interactions that are prevalent in modern parallel programs. Moreover, the synchronization achieved by these transactional memory systems is at the physical or memory level. This thesis advocates a position that memory synchronization problem for threads should be modeled and solved in terms of synchronization of underlying program values which have semantics associated with them. It presents optimistic synchronization techniques that address the semantic synchronization requirements of a parallel program instead. These techniques include methods to 1) enable optimistic transactions to recover from expensive sharing conflicts without discarding all the work made possible by the optimism 2) enable a hybrid pessimistic-optimistic form of concurrency control that lowers overheads 3) make synchronization value-aware and semantics-aware 4) enable finer grained consistency rules (than allowed by traditional optimistic TM models) therefore avoiding conflicts that do not enforce any semantic property required by the program. In addition to improving the expressibility of specific synchronization idioms all these techniques are also effective in improving parallel performance. This thesis formulates these techniques in terms of their purpose, the extensions to the language, the compiler as well as to the concurrency control runtime necessary to implement them. It also briefly presents an experimental evaluation of each of them on a variety of modern parallel workloads. These experiments show that these techniques significantly improve parallel performance and scalability over programs using state-of-the-art optimistic synchronization methods.

Thesis (M.C.S.)--Miami University, Dept. of Computer Science and Systems Analysis, 2009. / Title from first page of PDF document. Includes bibliographical references (p. 72-75).