Jochen Streicher

Interrupt synchronization in the CiAO operating system: experiences from implementing low-level system policies by AOP

Configurability is a major issue in the domain of embedded system software. Existing systems specifically lack good techniques to implement configurability of architectural OS concerns, such as the choice of isolation or synchronization policies to use. As such policies have a very cross-cutting character, aspects should provide good means to implement them in a configurable way. While our results show that this is in fact the case, 1) things could have been easier if additional language features were available, and, 2) additional means to influence the back-end code generation turned out to be very important. This paper presents our experiences in using AspectC++ to design and implement interrupt synchronization as a configurable property in the CiAO operating system.

Towards adjusting mobile devices to user's behaviour

Mobile devices are a special class of resource-constrained embedded devices. Computing power, memory, the available energy, and network bandwidth are often severely limited. These constrained resources require extensive optimization of a mobile system compared to larger systems. Any needless operation has to be avoided. Timeconsuming operations have to be started early on. For instance, loading files ideally starts before the user wants to access the file. So-called prefetching strategies optimize systems operation. Our goal is to adjust such strategies on the basis of logged system data. Optimization is then achieved by predicting an applications behavior based on facts learned from earlier runs on the same system. In this paper, we analyze system-calls on operating system level and compare two paradigms, namely server-based and device-based learning. The results could be used to optimize the runtime behaviour of mobile devices.

Open Smartphone Data for Structured Mobility and Utilization Analysis in Ubiquitous Systems

The development and evaluation of new data mining methods for ubiquitous environments and systems requires real data that were collected from real users. In this work, we present an open smartphone utilization and mobility data set that was generated with several devices and participants during a 4-month study. A particularity of this data set is the inclusion of low-level operating system data. Additionally to the description of the data, we also describe the process of collection and the privacy measures we applied. To demonstrate the utility of the data, we evaluate the quality of generative spatio-temporal models for “apps” and network cells, since these are required as a building block in general predictions of the resource consumption of ubiquitous systems.

Energy-Efficient GPS-Based Positioning in the Android Operating System

We present our ongoing collaborative work on EnDroid, an energy-efficient GPS-based positioning system for the Android Operating System. EnDroid is based on the EnTracked positioning system, developed at the University of Aarhus, Denmark. We describe the current prototypical state of our implementation and present our experiences and conclusions from preliminarily evaluating EnDroid on the Google Nexus One Smartphone. Although the preliminary results seem to support the approach, there are still several open questions, both at the application interface, as well as at the hardware management level.