Enhancing MINIX 3.X input/output performance

MINIX 3.X is an open-source operating system designed to be highly reliable, flexible, and secure. The kernel is extremely small and user processes, specialized servers and device driver runs as user-mode insulated processes. These features, the tiny amount of kernel code, and other aspects greatly enhance system reliability. The drawbacks of running device drivers in user-mode are the performance penalties on input/output ports access, kernel data structures access, interrupt indirect management, memory copy operations, etc.. As MINIX 3.X is based on the message transfer paradigm, device drivers must request those operations to the System Task (a special kernel representative process) sending request messages and waiting for reply messages increasing the system overhead. This article proposes a direct call mechanism that keeps system reliability running device drivers in user-mode but avoiding the message transfer, queuing, dequeuing and scheduling overheadWorkshop de Arquitecturas, Redes y Sistemas Operativos (WARSO)Red de Universidades con Carreras en Informática (RedUNCI

On participatory service provision at the network edge with community home gateways

Edge computing is considered as a technology to enable new types of services which operate at the network edge. There are important use cases in ambient intelligence and the Internet of Things (IoT) for edge computing driven by huge business potentials. Most of today's edge computing platforms, however, consist of proprietary gateways, which are either closed or fairly restricted to deploy any third-party services. In this paper we discuss a participatory edge computing system running on home gateways to serve as an open environment to deploy local services. We present first motivating use cases and review existing approaches and design considerations for the proposed system. Then we show our platform which materializes the principles of an open and participatory edge environment, to lower the entry barriers for service deployment at the network edge. By using containers, our platform can flexibly enable third-party services, and may serve as an infrastructure to support several application domains of ambient intelligence.Peer ReviewedPostprint (author's final draft

A file server for the DistriX prototype : a multitransputer UNIX system

Bibliography: pages 90-94.The DISTRIX operating system is a multiprocessor distributed operating system based on UNIX. It consists of a number of satellite processors connected to central servers. The system is derived from the MINIX operating system, compatible with UNIX Version 7. A remote procedure call interface is used in conjunction with a system wide, end-to-end communication protocol that connects satellite processors to the central servers. A cached file server provides access to all files and devices at the UNIX system call level. The design of the file server is discussed in depth and the performance evaluated. Additional information is given about the software and hardware used during the development of the project. The MINIX operating system has proved to be a good choice as the software base, but certain features have proved to be poorer. The Inmos transputer emerges as a processor with many useful features that eased the implementation

Enhancing MINIX 3.X input/output performance

MINIX 3.X is an open-source operating system designed to be highly reliable, flexible, and secure. The kernel is extremely small and user processes, specialized servers and device driver runs as user-mode insulated processes. These features, the tiny amount of kernel code, and other aspects greatly enhance system reliability. The drawbacks of running device drivers in user-mode are the performance penalties on input/output ports access, kernel data structures access, interrupt indirect management, memory copy operations, etc.. As MINIX 3.X is based on the message transfer paradigm, device drivers must request those operations to the System Task (a special kernel representative process) sending request messages and waiting for reply messages increasing the system overhead. This article proposes a direct call mechanism that keeps system reliability running device drivers in user-mode but avoiding the message transfer, queuing, dequeuing and scheduling overheadWorkshop de Arquitecturas, Redes y Sistemas Operativos (WARSO)Red de Universidades con Carreras en Informática (RedUNCI

LibrettOS: A Dynamically Adaptable Multiserver-Library OS

We present LibrettOS, an OS design that fuses two paradigms to simultaneously address issues of isolation, performance, compatibility, failure recoverability, and run-time upgrades. LibrettOS acts as a microkernel OS that runs servers in an isolated manner. LibrettOS can also act as a library OS when, for better performance, selected applications are granted exclusive access to virtual hardware resources such as storage and networking. Furthermore, applications can switch between the two OS modes with no interruption at run-time. LibrettOS has a uniquely distinguishing advantage in that, the two paradigms seamlessly coexist in the same OS, enabling users to simultaneously exploit their respective strengths (i.e., greater isolation, high performance). Systems code, such as device drivers, network stacks, and file systems remain identical in the two modes, enabling dynamic mode switching and reducing development and maintenance costs. To illustrate these design principles, we implemented a prototype of LibrettOS using rump kernels, allowing us to reuse existent, hardened NetBSD device drivers and a large ecosystem of POSIX/BSD-compatible applications. We use hardware (VM) virtualization to strongly isolate different rump kernel instances from each other. Because the original rumprun unikernel targeted a much simpler model for uniprocessor systems, we redesigned it to support multicore systems. Unlike kernel-bypass libraries such as DPDK, applications need not be modified to benefit from direct hardware access. LibrettOS also supports indirect access through a network server that we have developed. Applications remain uninterrupted even when network components fail or need to be upgraded. Finally, to efficiently use hardware resources, applications can dynamically switch between the indirect and direct modes based on their I/O load at run-time. [full abstract is in the paper]Comment: 16th ACM SIGPLAN/SIGOPS International Conference on Virtual Execution Environments (VEE '20), March 17, 2020, Lausanne, Switzerlan

On service optimization in community network micro-clouds

Cotutela Universitat Politècnica de Catalunya i KTH Royal Institute of TechnologyInternet coverage in the world is still weak and local communities are required to come together and build their own network infrastructures. People collaborate for the common goal of accessing the Internet and cloud services by building Community networks (CNs). The use of Internet cloud services has grown over the last decade. Community network cloud infrastructures (i.e. micro-clouds) have been introduced to run services inside the network, without the need to consume them from the Internet. CN micro-clouds aims for not only an improved service performance, but also an entry point for an alternative to Internet cloud services in CNs. However, the adaptation of the services to be used in CN micro-clouds have their own challenges since the use of low-capacity devices and wireless connections without a central management is predominant in CNs. Further, large and irregular topology of the network, high software and hardware diversity and different service requirements in CNs, makes the CN micro-clouds a challenging environment to run local services, and to achieve service performance and quality similar to Internet cloud services. In this thesis, our main objective is the optimization of services (performance, quality) in CN micro-clouds, facilitating entrance to other services and motivating members to make use of CN micro-cloud services as an alternative to Internet services. We present an approach to handle services in CN micro-cloud environments in order to improve service performance and quality that can be approximated to Internet services, while also giving to the community motivation to use CN micro-cloud services. Furthermore, we break the problem into different levels (resource, service and middleware), propose a model that provides improvements for each level and contribute with information that helps to support the improvements (in terms of service performance and quality) in the other levels. At the resource level, we facilitate the use of community devices by utilizing virtualization techniques that isolate and manage CN micro-cloud services in order to have a multi-purpose environment that fosters services in the CN micro-cloud environment. At the service level, we build a monitoring tool tailored for CN micro-clouds that helps us to analyze service behavior and performance in CN micro-clouds. Subsequently, the information gathered enables adaptation of the services to the environment in order to improve their quality and performance under CN environments. At the middleware level, we build overlay networks as the main communication system according to the social information in order to improve paths and routes of the nodes, and improve transmission of data across the network by utilizing the relationships already established in the social network or community of practices that are related to the CNs. Therefore, service performance in CN micro-clouds can become more stable with respect to resource usage, performance and user perceived quality.Acceder a Internet sigue siendo un reto en muchas partes del mundo y las comunidades locales se ven en la necesidad de colaborar para construir sus propias infraestructuras de red. Los usuarios colaboran por el objetivo común de acceder a Internet y a los servicios en la nube construyendo redes comunitarias (RC). El uso de servicios de Internet en la nube ha crecido durante la última década. Las infraestructuras de nube en redes comunitarias (i.e., micronubes) han aparecido para albergar servicios dentro de las mismas redes, sin tener que acceder a Internet para usarlos. Las micronubes de las RC no solo tienen por objetivo ofrecer un mejor rendimiento, sino también ser la puerta de entrada en las RC hacia una alternativa a los servicios de Internet en la nube. Sin embargo, la adaptación de los servicios para ser usados en micronubes de RC conlleva sus retos ya que el uso de dispositivos de recursos limitados y de conexiones inalámbricas sin una gestión centralizada predominan en las RC. Más aún, la amplia e irregular topología de la red, la diversidad en el hardware y el software y los diferentes requisitos de los servicios en RC convierten en un desafío albergar servicios locales en micronubes de RC y obtener un rendimiento y una calidad del servicio comparables a los servicios de Internet en la nube. Esta tesis tiene por objetivo la optimización de servicios (rendimiento, calidad) en micronubes de RC, facilitando la entrada a otros servicios y motivando a sus miembros a usar los servicios en la micronube de RC como una alternativa a los servicios en Internet. Presentamos una aproximación para gestionar los servicios en entornos de micronube de RC para mejorar su rendimiento y calidad comparable a los servicios en Internet, a la vez que proporcionamos a la comunidad motivación para usar los servicios de micronube en RC. Además, dividimos el problema en distintos niveles (recursos, servicios y middleware), proponemos un modelo que proporciona mejoras para cada nivel y contribuye con información que apoya las mejoras (en términos de rendimiento y calidad de los servicios) en los otros niveles. En el nivel de los recursos, facilitamos el uso de dispositivos comunitarios al emplear técnicas de virtualización que aíslan y gestionan los servicios en micronubes de RC para obtener un entorno multipropósito que fomenta los servicios en el entorno de micronube de RC. En el nivel de servicio, construimos una herramienta de monitorización a la medida de las micronubes de RC que nos ayuda a analizar el comportamiento de los servicios y su rendimiento en micronubes de RC. Luego, la información recopilada permite adaptar los servicios al entorno para mejorar su calidad y rendimiento bajo las condiciones de una RC. En el nivel de middleware, construimos redes de overlay que actúan como el sistema de comunicación principal de acuerdo a información social para mejorar los caminos y las rutas de los nodos y mejoramos la transmisión de datos a lo largo de la red al utilizar las relaciones preestablecidas en la red social o la comunidad de prácticas que están relacionadas con las RC. De este modo, el rendimiento en las micronubes de RC puede devenir más estable respecto al uso de recursos, el rendimiento y la calidad percibidas por el usuario.Postprint (published version

Articulating the speed(s) of the Internet: the case of open source/free software

"The Internet is widely considered as a key factor of speeding up social and cultural change. It represents the merging of information and communication technologies and enables flows of information and capital, and communication and co-operation regardless of space and, possibly, time. The paper explores the example of Open Source/Free Software development, i.e. software development in self-organised projects based on a considerable share of voluntary work. Here, we find complex articulations of speeding up and slowing down technological development. Open Source/Free Software projects complement the logic of speeding up technological progress and of obsolescence with a reflexive logic of optionality, variety and sustainability which addresses the accessibility of technology and knowledge as a precondition for future creativity beyond markets and organisations." (author's abstract

An X-Windows monitoring system for SunOS MINIX

Most operating systems instructors recognise the value of practical work in their courses. Laboratory-style practical work offers the student the opportunity to put their theoretical knowledge into practice. The incorporation of laboratory work into an operating systems course requires the use of practical aids that illustrate or reinforce the important concepts of operating systems theory. The design and implementation of such an aid, the SunOS MINIX Monitoring System, is described. This system is based on SunOS MINIX, a version of the MINIX instructional operating system that runs as a user process under SunOS. The aim of this project was to take advantage of the hosted nature of SunOS MINIX by constructing a communications interface that would permit it to be monitored and controlled by external (SunOS) processes. The monitoring system includes a set of tools allowing a user to inspect, monitor and control a running instance of the SunOS MINIX operating system