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With the growth of the number of Web services published over Internet, identifying composite services by taking into account both functional and non-functional requirements of end users has become a real challenge that needs to be addressed. This challenge is aggravated in the case of situations requiring adaptation to user context. To overcome these challenges, we propose a solution that enables...
We propose a novel sampling algorithm for the von Mises–Fisher distribution on the unit hypersphere. Unlike previous works, we show a solution for an arbitrary number of dimensions without requiring rejection sampling. As a result, the proposed algorithm has a deterministic runtime. The key idea consists in applying the inversion method to a one-dimensional subproblem and analytically calculating...
Software applications are increasingly desirable to adapt to varying execution environments and diverse user requirements to support runtime adaptation. Behavioral variations are generally modularized to handle variability. Depending on activating or deactivating relevant variations dynamically due to continuous context changes, a required behavioral variant specific to contexts is subsequently generated...
Building a cyber-physical system consisting of many reactive elements that continually interact with each other may require considerable efforts to ensure that it behaves as desired. The scale of the issues to tackle is much expanded when it comprises human-factors to analyze and change (e.g persuasion). In this paper, a development methodology is proposed for building the kind of system that developer...
The tremendous increase in the size and heterogeneity of supercomputers makes it very difficult to predict the performance of a scheduling algorithm. In this context, relying on purely static scheduling and resource allocation strategies, that make scheduling and allocation decisions based on the dependency graph and the platform description, is expected to lead to large and unpredictable make spans...
In this paper we address the problem of massive event trace sizes, one of the most urgent challenges in the performance analysis of large-scale parallel applications. Reducing trace sizes during the application runtime decreases application slow down, eliminates measurement bias, and cuts down stress on the underlying file system. Previous approaches use static filters to decrease trace size, which...
Redundant computations can severely degrade performance in HPC applications. Redundant computations arise due to various causes such as developers' inattention to performance, inappropriate choice of algorithms, and inefficient code generation, among others. Aliasing, limited optimization scopes, and insensitivity to input and execution contexts act as severe deterrents to static program analysis...
Using GPUs reduces execution time of many applications but increases acquisition cost and power consumption. Furthermore, GPUs usually attain a relatively low utilization. In this context, remote GPU virtualization solutions were recently created to overcome the drawbacks of using GPUs. Currently, many different remote GPU virtualization frameworks exist, all of them presenting very different characteristics...
OpenCL is a portable interface that can be used to program cluster nodes with heterogeneous compute devices. The OpenCL specification tightly binds its workflow abstraction, or "command queue," to a specific device for the entire program. For best performance, the user has to find the ideal queue -- device mapping at command queue creation time, an effort that requires a thorough understanding...
In an execution of a large scale program, even a simple observable behavior may be generated by a wide range of the source code. To comprehend how such a behavior is implemented in the code, a debugger would be helpful. However, when using a debugger, developers often encounter several types of cumbersome tasks and are often confused by the huge and complicated runtime information. To support such...
The long-term goal of the work presented here is the automatic instrumentation of C programs with temporal property checkers to perform the runtime verification that these programs behave as expected, both for debugging purposes and for security or safety-oriented monitoring. This paper describes our first results towards this objective. To give requirements engineers or software developers the possibility...
This paper introduces a new approach for the online detection of performance anomalies in cloud virtual machines (VMs). It is designed for cloud infrastructure providers to detect during runtime unknown anomalies that may still be observed in complex modern systems hosted on VMs. The approach is drawn on data stream clustering of per-VM monitoring data and detects at a fine granularity where anomalies...
We classify the complexity of the LTL satisfiability and model checking problems for several standard parameterisations. The investigated parameters are temporal depth, number of propositional variables and formula treewidth, resp., pathwidth. We show that all operator fragments of LTL under the investigated parameterisations are intractable in the sense of parameterised complexity.
Operations such as upgrade or redeployment are an important cause of system outages. Diagnosing such errors at runtime poses significant challenges. In this paper, we propose an error diagnosis approach using Bayesian Networks. Each node in the network captures the potential (root) causes of operational errors and its probability under different operational contexts. Once an operational error is detected,...
Nowadays, it is not possible to imagine our daily life without support of technical systems. And even more so, when it comes to complex tasks which require specific knowledge, prompt reaction to situation changes and intelligent process coordination. We propose a concept of generic workflows for application domains with complex, critical and highly dynamic situations. To obtain the required adaptation...
The use of Cloud infrastructures together with provisioning technologies can be successfully applied in scenarios where resources are only needed rarely and irregularly, for example simulation workflows in the eScience domain. There has already been proposed a solution for the on-demand provisioning of services required by workflows, but how to automatically provision the needed workflow middleware...
Systems-of-systems (SoS) represent a class of systems resulted from the interaction among independent systems that cooperate to form a larger and more complex system aiming at accomplishing global missions. An inherent characteristic of SoS is the high heterogeneity of their constituent systems, which are distributed, independent, and developed with different technologies. In addition, SoS are highly...
Software evolution has been extensively studied in the past decade for various properties and interesting patterns. In this work, we study the effect of evolution on branch prediction techniques. Typically for any program, at the hardware level, all dynamic branch prediction strategies learn the branch behaviors at run time and later re-use them to predict the direction of future branches. The duration...
As the core density of future processors keeps increasing, MPI+Threads is becoming a promising programming model for large scale SMP clusters. Generally speaking, hybrid MPI+Threads runtime can largely improve intra-node parallelism and data sharing on shared-memory architectures. However, it does not help much on inter-node communication due to the inefficient integration of existing communication...
As applications deployed in a smart space share the same physical environment, they may interfere (or even conflict) with one another. To guarantee the performance and user experience of the entire smart space, mechanisms for handling such interferes (or conflicts) have to be introduced. We believe that conflicts among multiple applications are caused by their different requirements and impacts on...
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