771 research outputs found
CONFIGEN: A tool for managing configuration options
This paper introduces CONFIGEN, a tool that helps modularizing software.
CONFIGEN allows the developer to select a set of elementary components for his
software through an interactive interface. Configuration files for use by
C/assembly code and Makefiles are then automatically generated, and we
successfully used it as a helper tool for complex system software refactoring.
CONFIGEN is based on propositional logic, and its implementation faces hard
theoretical problems.Comment: In Proceedings LoCoCo 2010, arXiv:1007.083
Towards a formally designed and verified embedded operating system: case study using the B method
The dramatic growth in practical applications for iris biometrics has been accompanied
by relevant developments in the underlying algorithms and techniques. Along
with the research focused on near-infrared images captured with subject cooperation,
e orts are being made to minimize the trade-o between the quality of the captured
data and the recognition accuracy on less constrained environments, where images are
obtained at the visible wavelength, at increased distances, over simpli ed acquisition
protocols and adverse lightning conditions. At a rst stage, interpolation e ects on
normalization process are addressed, pointing the outcomes in the overall recognition
error rates. Secondly, a couple of post-processing steps to the Daugman's approach
are performed, attempting to increase its performance in the particular unconstrained
environments this thesis assumes. Analysis on both frequency and spatial domains
and nally pattern recognition methods are applied in such e orts. This thesis embodies
the study on how subject recognition can be achieved, without his cooperation,
making use of iris data captured at-a-distance, on-the-move and at visible wavelength
conditions. Widely used methods designed for constrained scenarios are analyzed
Adding SMP support to fastpaths in an L4 microkernel
Fastpaths are a method of optimization which relies on treating the most commonly executed cases of certain functions in a privileged manner, such that behaviour is not modified, but execution time is reduced.Fastpaths play an important role on improving paravirtualization performance offered by an L4 microkernel.In this article we redesign two existing fastpaths in an L4 microkernel for the purpose of adding SMP support.We then put these fastpaths through a series of regression and performance tests to determine if the design is correct and what performance benefits we can expect by using them on a multiprocessor system
The Case for a Factored Operating System (fos)
The next decade will afford us computer chips with 1,000 - 10,000 cores on a single piece of silicon. Contemporary operating systems have been designed to operate on a single core or small number of cores and hence are not well suited to manage and provide operating system services at such large scale. Managing 10,000 cores is so fundamentally different from managing two cores that the traditional evolutionary approach of operating system optimization will cease to work. The fundamental design of operating systems and operating system data structures must be rethought. This work begins by documenting the scalability problems of contemporary operating systems. These studies are used to motivate the design of a factored operating system (fos). fos is a new operating system targeting 1000+ core multicore systems where space sharing replaces traditional time sharing to increase scalability. fos is built as a collection of Internet inspired services. Each operating system service is factored into a fleet of communicating servers which in aggregate implement a system service. These servers are designed much in the way that distributed Internet services are designed, but instead of providing high level Internet services, these servers provide traditional kernel services and manage traditional kernel data structures in a factored, spatially distributed manner. The servers are bound to distinct processing cores and by doing so do not fight with end user applications for implicit resources such as TLBs and caches. Also, spatial distribution of these OS services facilitates locality as many operations only need to communicate with the nearest server for a given service
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