An occam Style Communications System for UNIX Networks

This document describes the design of a communications system which provides occam style communications primitives under a Unix environment, using TCP/IP protocols, and any number of other protocols deemed suitable as underlying transport layers. The system will integrate with a low overhead scheduler/kernel without incurring significant costs to the execution of processes within the run time environment. A survey of relevant occam and occam3 features and related research is followed by a look at the Unix and TCP/IP facilities which determine our working constraints, and a description of the T9000 transputer's Virtual Channel Processor, which was instrumental in our formulation. Drawing from the information presented here, a design for the communications system is subsequently proposed. Finally, a preliminary investigation of methods for lightweight access control to shared resources in an environment which does not provide support for critical sections, semaphores, or busy waiting, is made. This is presented with relevance to mutual exclusion problems which arise within the proposed design. Future directions for the evolution of this project are discussed in conclusion

State of the art survey of network operating systems development

The results of the State-of-the-Art Survey of Network Operating Systems (NOS) performed for Goddard Space Flight Center are presented. NOS functional characteristics are presented in terms of user communication data migration, job migration, network control, and common functional categories. Products (current or future) as well as research and prototyping efforts are summarized. The NOS products which are revelant to the space station and its activities are evaluated

Interprocess communication in highly distributed systems

Issued as Final technical report, Project no. G-36-632Final technical report has title: Interprocess communication in highly distributed system

Study of Tools Interoperability

Interoperability of tools usually refers to a combination of methods and techniques that address the problem of making a collection of tools to work together. In this study we survey different notions that are used in this context: interoperability, interaction and integration. We point out relation between these notions, and how it maps to the interoperability problem. We narrow the problem area to the tools development in academia. Tools developed in such environment have a small basis for development, documentation and maintenance. We scrutinise some of the problems and potential solutions related with tools interoperability in such environment. Moreover, we look at two tools developed in the Formal Methods and Tools group1, and analyse the use of different integration techniques

Deep Space Network information system architecture study

The purpose of this article is to describe an architecture for the Deep Space Network (DSN) information system in the years 2000-2010 and to provide guidelines for its evolution during the 1990s. The study scope is defined to be from the front-end areas at the antennas to the end users (spacecraft teams, principal investigators, archival storage systems, and non-NASA partners). The architectural vision provides guidance for major DSN implementation efforts during the next decade. A strong motivation for the study is an expected dramatic improvement in information-systems technologies, such as the following: computer processing, automation technology (including knowledge-based systems), networking and data transport, software and hardware engineering, and human-interface technology. The proposed Ground Information System has the following major features: unified architecture from the front-end area to the end user; open-systems standards to achieve interoperability; DSN production of level 0 data; delivery of level 0 data from the Deep Space Communications Complex, if desired; dedicated telemetry processors for each receiver; security against unauthorized access and errors; and highly automated monitor and control

Study of fault-tolerant software technology

Presented is an overview of the current state of the art of fault-tolerant software and an analysis of quantitative techniques and models developed to assess its impact. It examines research efforts as well as experience gained from commercial application of these techniques. The paper also addresses the computer architecture and design implications on hardware, operating systems and programming languages (including Ada) of using fault-tolerant software in real-time aerospace applications. It concludes that fault-tolerant software has progressed beyond the pure research state. The paper also finds that, although not perfectly matched, newer architectural and language capabilities provide many of the notations and functions needed to effectively and efficiently implement software fault-tolerance

Dynamic File-Access Characteristics of a Production Parallel Scientific Workload

Multiprocessors have permitted astounding increases in computational performance, but many cannot meet the intense I/O requirements of some scientific applications. An important component of any solution to this I/O bottleneck is a parallel file system that can provide high-bandwidth access to tremendous amounts of data in parallel to hundreds or thousands of processors. Most successful systems are based on a solid understanding of the characteristics of the expected workload, but until now there have been no comprehensive workload characterizations of multiprocessor file systems. We began the CHARISMA project in an attempt to fill that gap. We instrumented the common node library on the iPSC/860 at NASA Ames to record all file-related activity over a two-week period. Our instrumentation is different from previous efforts in that it collects information about every read and write request and about the mix of jobs running in the machine (rather than from selected applications). The trace analysis in this paper leads to many recommendations for designers of multiprocessor file systems. First, the file system should support simultaneous access to many different files by many jobs. Second, it should expect to see many small requests, predominantly sequential and regular access patterns (although of a different form than in uniprocessors), little or no concurrent file-sharing between jobs, significant byte- and block-sharing between processes within jobs, and strong interprocess locality. Third, our trace-driven simulations showed that these characteristics led to great success in caching, both at the compute nodes and at the I/O nodes. Finally, we recommend supporting strided I/O requests in the file-system interface, to reduce overhead and allow more performance optimization by the file system

Coprocessor integration for real-time event processing in particle physics detectors

Els experiments de física d’altes energies actuals disposen d’acceleradors amb més energía, sensors més precisos i formes més flexibles de recopilar les dades. Aquesta ràpida evolució requereix de més capacitat de càlcul; els processadors massivament paral·lels, com ara les targes acceleradores gràfiques, ens posen a l’abast aquesta major capacitat de càlcul a un cost sensiblement inferior a les CPUs tradicionals. L’ús d’aquest tipus de processadors requereix, però, de nous algoritmes i nous enfocaments de l’organització de les dades que són difícils d’integrar en els programaris actuals. En aquest treball s’exploren els problemes derivats de l’ús d’algoritmes paral·lels en els entorns de programari existents, orientats a CPUs, i es proposa una solució, en forma de servei, que comunica amb els diversos pipelines que processen els esdeveniments procedents de les col·lisions de partícules, recull les dades en lots i els envia als algoritmes corrent sobre els processadors massivament paral·lels. Aquest servei s’integra en Gaudí - l’entorn de software de dos dels quatre experiments principals del Gran Col·lisionador d’Hadrons. S’examina el sobrecost que el servei afegeix als algoritmes paral·lels. S’estudia un cas d´ùs del servei per fer una reconstrucció paral·lela de les traces detectades en el VELO Pixel, el subdetector encarregat de la detecció de vèrtex en l’upgrade de LHCb. Per aquest cas, s’observen les característiques del rendiment en funció de la mida dels lots de dades. Finalment, les conclusions en posen en el context dels requeriments del sistema de trigger de LHCb.La física de altas energías dispone actualmente de aceleradores con energías mayores, sensores más precisos y métodos de recopilación de datos más flexibles que nunca. Su rápido progreso necesita aún más potencia de cálculo; el hardware masivamente paralelo, como las unidades de procesamiento gráfico, nos brinda esta potencia a un coste mucho más bajo que las CPUs tradicionales. Sin embargo, para usar eficientemente este hardware necesitamos algoritmos nuevos y nuevos enfoques de organización de datos difíciles de integrarse con el software existente. En este trabajo, se investiga cómo se pueden usar estos algoritmos paralelos en las infraestructuras de software ya existentes y que están orientadas a CPUs. Se propone una solución en forma de un servicio que comunica con los diversos pipelines que procesan los eventos de las correspondientes colisiones de particulas, reúne los datos en lotes y se los entrega a los algoritmos paralelos acelerados por hardware. Este servicio se integra con Gaudí — la infraestructura del entorno de software que usan dos de los cuatro gran experimentos del Gran Colisionador de Hadrones. Se examinan los costes añadidos por el servicio en los algoritmos paralelos. Se estudia un caso de uso del servicio para ejecutar un algoritmo paralelo para el VELO Pixel (el subdetector encargado de la localización de vértices en el upgrade del experimento LHCb) y se estudian las características de rendimiento de los distintos tamaños de lotes de datos. Finalmente, las conclusiones se contextualizan dentro la perspectiva de los requerimientos para el sistema de trigger de LHCb.High-energy physics experiments today have higher energies, more accurate sensors, and more flexible means of data collection than ever before. Their rapid progress requires ever more computational power; and massively parallel hardware, such as graphics cards, holds the promise to provide this power at a much lower cost than traditional CPUs. Yet, using this hardware requires new algorithms and new approaches to organizing data that can be difficult to integrate with existing software. In this work, I explore the problem of using parallel algorithms within existing CPU-orientated frameworks and propose a compromise between the different trade-offs. The solution is a service that communicates with multiple event-processing pipelines, gathers data into batches, and submits them to hardware-accelerated parallel algorithms. I integrate this service with Gaudi — a framework underlying the software environments of two of the four major experiments at the Large Hadron Collider. I examine the overhead the service adds to parallel algorithms. I perform a case study of using the service to run a parallel track reconstruction algorithm for the LHCb experiment's prospective VELO Pixel subdetector and look at the performance characteristics of using different data batch sizes. Finally, I put the findings into perspective within the context of the LHCb trigger's requirements

On component-oriented access control in lightweight virtualized server environments

2017 Fall.Includes bibliographical references.With the advancements in contemporary multi-core CPU architectures and increase in main memory capacity, it is now possible for a server operating system (OS), such as Linux, to handle a large number of concurrent services on a single server instance. Individual components of such services may run in different isolated runtime environments, such as chrooted jails or related forms of OS-level containers, and may need restricted access to system resources and the ability to share data and coordinate with each other in a regulated and secure manner. In this dissertation we describe our work on the access control framework for policy formulation, management, and enforcement that allows access to OS resources and also permits controlled data sharing and coordination for service components running in disjoint containerized environments within a single Linux OS server instance. The framework consists of two models and the policy formulation is based on the concept of policy classes for ease of administration and enforcement. The policy classes are managed and enforced through a Lightweight Policy Machine for Linux (LPM) that acts as the centralized reference monitor and provides a uniform interface for regulating access to system resources and requesting data and control objects. We present the details of our framework and also discuss the preliminary implementation and evaluation to demonstrate the feasibility of our approach