Using The Nanvix Operating System in Undergraduate Operating System Courses

National audienceOperating Systems (OSs) have an important position in the Computer Science curriculum. When students face this subject, they study core concepts, mechanisms and strategies that apply to several fields. To support practical lectures in an OSs course, instructors may adopt an OS on which students can work, exercising their knowledge and enhancing their practical skills. In this context, we present Nanvix, a new OS designed to address this use in undergraduate OSs courses. We introduce a flexible assignment-based teaching methodology for our OS, and we assess the effectiveness of this methodology by applying it in the OSs course of the Pontifical Catholic University of Minas Gerais. When using Nanvix, the average score of the students in the course increased in 11.2%, and the failure rate dropped 47.7%. Moreover, we observed that with Nanvix students got more motivated and interested in the OSs field

An inter-cluster communication facility for lightweight manycore processors in the Nanvix OS

TCC(graduação) - Universidade Federal de Santa Catarina. Centro Tecnológico. Ciências da Computação.Em conjunto com a maior escalabilidade e eficiência energética, os processadores lightweight manycores trouxeram um novo conjunto de desafios no desenvolvimento de software provenientes de suas particularidades arquiteturais. Neste contexto, sistemas operacionais tornam o desenvolvimento de aplicações menos onerosos, menos suscetíveis a erros e mais eficientes. A camada de abstração provida pelos sistemas operacionais suprime as características do hardware sob uma perspectiva simplificada e eficaz. No entanto, parte dos desafios de desenvolvimento encontrados em lightweight manycores deriva diretamente de runtimes e sistemas operacionais existentes, que não lidam completamente com a complexidade arquitetural desses processadores. Acreditamos que sistemas operacionais para a próxima geração de lightweight manycores necessitam ser repensados a partir de seus conceitos básicos considerando as severas restrições arquiteturais. Em particular, as abstrações de comunicação desempenham um papel crucial na escalabilidade e desempenho das aplicações devido à natureza distribuída dos manycores. O objetivo deste trabalho é propor mecanismos de comunicação entre clusters para o processador manycore emergente MPPA-256. Estes mecanismos fazem parte de uma Camada de Abstração de Hardware (HAL) genérica e flexível para lightweight manycores que lida diretamente com os principais problemas encontrados no projeto de um sistema operacional para esses processadores. Sob estes mecanismos, serviços de comunicação também serão propostos para um sistema operacional baseado no modelo microkernel, que busca fornecer um esqueleto básico para as abstrações de comunicação. As contribuições deste trabalho estão inseridas em um contexto de pesquisa mais amplo, que procura investigar a criação de um sistema operacional distribuído baseado em uma abordagem multikernel, denominado Nanvix OS. O Nanvix OS se concentrará em questões de programabilidade e portabilidade através de um sistema operacional compatível com o padrão POSIX para lightweight manycore. Os resultados mostram como algoritmos distribuídos conhecidos podem ser eficientemente suportados pelo Nanvix OS e incentivam melhorias providas pelo uso adequado dos aceleradores de Acesso Direto à Memória (DMA).Jointly with further scalability and energy efficiency, lightweight manycores brought a new set of challenges in software development coming from their architectural particularities. In this context, Operating Systems (OSs) make application development less costly, less error-prone, and more efficient. The abstraction layer provided by OSs suppresses hardware characteristics from a simplified and productive perspective. However, part of the development challenges encountered in lightweight manycores stems from the existing runtimes and OSs, which do not entirely address the complexity of these processors. We believe that OSs for the next generation of lightweight manycores must be redesigned from scratch to cope with their tight architectural constraints. In particular, communication abstractions play a crucial role in application scalability and performance due to the distributed nature of manycores. The purpose of this undergraduate dissertation is to propose an inter-cluster communication facility for the emerging manycore MPPA-256 processor. This facility is part of a generic and flexible Hardware Abstraction Layer (HAL) that deals directly with the key issues encountered in designing an OS for these processors. Above this facility, communication services will also be proposed for an OS based on the microkernel model, which seeks to provide a basic framework for communication abstractions. The contributions of this undergraduate dissertation are embedded in a broader research context that aims to investigate the creation of a distributed OS based on a multikernel approach, called Nanvix OS. Nanvix OS focuses on programmability and portability issues for manycores through a POSIX-compliant OS. The results present how well known distributed algorithms can be efficiently supported by Nanvix OS and encourage improvements provided by the proper use of Direct memory access (DMA) accelerators

RMem: An OS Service for Transparent Remote Memory Access in Lightweight Manycores

International audienceLightweight manycores deliver high performance and scal-ability at low power consumption. However, architectural intricacies of these processors impose programmability challenges that keep them away from mass adoption. While several efforts aim at introducing parallel programming environments to lightweight manycores, few initiatives are concerned about how to design rich Operating Systems (OSs) to them. In this work, we focus on the open challenges that arise from constrained memory subsystems of lightweight manycores, such as the presence of multiple address spaces and limited on-chip memory. To cope with transparent data access in this scenario, we introduce an OS service, named RMem. This service provides a shared memory abstraction over multiple address spaces and exposes system calls that enable one-sided communication on top of this abstraction. We implemented a prototype of our service in the Nanvix research OS, and we deployed the system the Kalray MPPA-256 lightweight manycore. Our experimental results with a microbenchmark unveiled that, while exposing an easier-to-program interface, the RMem Service may deliver about 91% of the write performance and up to 2.4× better read performance than the primitives in the libraries of the experimental platform

Using The Nanvix Operating System in Undergraduate Operating System Courses

National audienceOperating Systems (OSs) have an important position in the Computer Science curriculum. When students face this subject, they study core concepts, mechanisms and strategies that apply to several fields. To support practical lectures in an OSs course, instructors may adopt an OS on which students can work, exercising their knowledge and enhancing their practical skills. In this context, we present Nanvix, a new OS designed to address this use in undergraduate OSs courses. We introduce a flexible assignment-based teaching methodology for our OS, and we assess the effectiveness of this methodology by applying it in the OSs course of the Pontifical Catholic University of Minas Gerais. When using Nanvix, the average score of the students in the course increased in 11.2%, and the failure rate dropped 47.7%. Moreover, we observed that with Nanvix students got more motivated and interested in the OSs field