David A. Bacigalupo

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Before an application modelled as a Directed Acyclic Graph (DAG) is executed on a heterogeneous system, a DAG mapping policy is often enacted. After mapping, the tasks (in the DAG-based application) to be executed at each computational resource are determined. The tasks are then sent to the corresponding resources, where they are orchestrated in the(More)
This paper reviews current cloud computing business models and presents proposals on how organisations can achieve sustainability by adopting appropriate models. We classify cloud computing business models into eight types: (1) Service Provider and Service Orientation; (2) Support and Services Contracts; (3) In-House Private Clouds; (4) All-In-One(More)
Predictive performance models of e-Commerce applications will allow Grid workload managers to provide e-Commerce clients with qualities of service (QoS) whilst making efficient use of resources. This paper demonstrates the use of two 'coarse-grained' modelling approaches (based on layered queuing modelling and historical performance data analysis) for(More)
Response time predictions for workload on new server architectures can enhance Service Level Agreement–based resource management. This paper evaluates three performance prediction methods using a distributed enterprise application benchmark. The historical method makes predictions by extrapolating from previously gathered performance data, while the layered(More)
The purpose of the TeciRes project was to conduct a technical review of the current landscape within cloud computing to establish the extent to which existing solutions meet encountered and envisioned requirements for using emerging cloud technologies, in particular those which enable computing and storage cloud facilities for research in Higher Education(More)
The automatic allocation of enterprise workload to resources can be enhanced by being able to make what-if response time predictions whilst different allocations are being considered. We experimentally investigate an historical and a layered queuing performance model and show how they can provide a good level of support for a dynamic − urgent cloud(More)
Distributed e-business application platforms such as the web services framework will require sophisticated workload management infrastructures for the routing of client requests to the most appropriate services. This paper introduces a novel and dynamic predictive framework that uses both analytical performance modelling and historical data to extrapolate a(More)
Container-managed persistence is an essential technology as it dramatically simplifies the implementation of enterprise data access. However it can also impose a significant overhead on the performance of the application at runtime. This paper presents a layered queuing performance model for predicting the effect of adding or removing container-managed(More)
Two common approaches for predicting the response times of distributed enterprise applications on new server architectures are solving queuing models and extrapolating from previously gathered performance data. The dynamic recalibration of a layered queuing model and a historical model is investigated experimentally using the IBM Websphere Performance(More)