Exploiting tightly-coupled cores

As we move steadily through the multicore era, and the number of processing cores on each chip continues to rise, parallel computation becomes increasingly important. However, parallelising an application is often difficult because of dependencies between different regions of code which require cores to communicate. Communication is usually slow compared to computation, and so restricts the opportunities for profitable parallelisation. In this work, I explore the opportunities provided when communication between cores has a very low latency and low energy cost. I observe that there are many different ways in which multiple cores can be used to execute a program, allowing more parallelism to be exploited in more situations, and also providing energy savings in some cases. Individual cores can be made very simple and efficient because they do not need to exploit parallelism internally. The communication patterns between cores can be updated frequently to reflect the parallelism available at the time, allowing better utilisation than specialised hardware which is used infrequently. In this dissertation I introduce Loki: a homogeneous, tiled architecture made up of many simple, tightly-coupled cores. I demonstrate the benefits in both performance and energy consumption which can be achieved with this arrangement and observe that it is also likely to have lower design and validation costs and be easier to optimise. I then determine exactly where the performance bottlenecks of the design are, and where the energy is consumed, and look into some more-advanced optimisations which can make parallelism even more profitable

The safety of industrially-based controllers incorporating software

This thesis is concerned with the safety of industrial controllers which incorporate software. Software safety is compared with software reliability as a means of discussing the special concerns of safety. Definitions are given for the terms hazard, risk, danger and safe. A relationship between these terms has been attempted and the philosophy of safety is discussed. A formal definition of software safety is given. The factors influencing the development of software are examined. The subjectivity of safety is discussed in the context of safety measurement being a conjoint measurement. Methods of assessing the risk resulting from the use of software are described along with a discussion on the impracticability of using state transition diagrams to isolate catastrophic failure conditions. Categories of danger are discussed and three categories are advanced. The structuring of the software for safety is discussed and the principle of using safety modules and integrity locks is proposed. In discussing the reasons for errors remaining present in the software after testing two methods of measurement are suggested; Plexus and Fallibility Index. The need to declare variables is discussed. An experiment involving 119 volunteers was conducted to examine the influence of the length of variable names'on the correct usage. It was found that variables with a character length of 7 have a better probability of correct interpretation than others. The methods of assessing safety are discussed and the measurements proposed were applied to a commercially available product in the form of a Software Safety Audit. It is concluded that some aspects of the safety of controllers incorporating software can be quantified and that further research is needed

Bringing Model Checking Closer To Practical Software Engineering

Bal, H.E. [Promotor]Templon, J.A. [Copromotor]Willemse, T.A.C. [Copromotor

Using Virtualisation to Protect Against Zero-Day Attacks

Bal, H.E. [Promotor]Bos, H.J. [Copromotor

Rethinking Density. Art, Culture, and Urban Practices

Rethinking Density: Art, Culture, and Urban Practices considers new perspectives and discussions related to the category of density, which for a long time has been part of urban-planning discourses and is now regaining the attention of artists and practitioners from a number of different disciplines. In an interplay of models, coping strategies, and experimental approaches, this publication combines research from cultural studies, artistic research, sound studies as well as architectural and urban theory. The issues discussed include the consideration of retroactive architectural design as a means to retrace the historical layers of a city, a proposal for spacesharing concepts as instruments for urban revitalization processes, and a case study on the potential for new sonic social spaces as subversive modes to undermine prevailing power structures