Caladan: a distributed meta-OS for data center disaggregation

Data center resource disaggregation promises cost savings by pool-ing compute, storage and memory resources into separate, net-worked nodes. The benefits of this model are clear, but a closer lookshows that its full performance and efficiency potential cannot beeasily realized. Existing systems use CPUs pervasively to interface ar-bitrary devices with the network and to orchestrate communicationamong them, reducing the benefits of disaggregation.In this paper we presentCaladan, a novel system with a trusteduni-versal resource fabricthat interconnects all resources and efficientlyoffloads the system and application control planes to SmartNICs,freeing server CPUs to execute application logic. Caladan offersthree core services: capability-driven distributed name space, virtualdevices, and direct inter-device communications. These servicesare implemented in a trustedmeta-kernelthat executes in per-nodeSmartNICs. Low-level device drivers running on the commodity hostOS are used for setting up accelerators and I/O devices, and exposingthem to Caladan. Applications run in a distributed fashion acrossCPUs and multiple accelerators, which in turn can directly performI/O, i.e., access files, other accelerators or host services. Our dis-tributed dataflow runtime runs on top of this substrate. It orchestratesthe distributed execution, connecting disaggregated resources usingdata transfers and inter-device communication, while eliminatingthe performance bottlenecks of the traditional CPU-centric design

Multi-resource management in embedded real-time systems

This thesis addresses the problem of online multi-resource management in embedded real-time systems. It focuses on three research questions. The first question concentrates on how to design an efficient hierarchical scheduling framework for supporting independent development and analysis of component based systems, to provide temporal isolation between components. The second question investigates how to change the mapping of resources to tasks and components during run-time efficiently and predictably, and how to analyze the latency of such a system mode change in systems comprised of several scalable components. The third question deals with the scheduling and analysis of a set of parallel-tasks with real-time constraints which require simultaneous access to several different resources. For providing temporal isolation we chose a reservation-based approach. We first focused on processor reservations, where timed events play an important role. Common examples are task deadlines, periodic release of tasks, budget replenishment and budget depletion. Efficient timer management is therefore essential. We investigated the overheads in traditional timer management techniques and presented a mechanism called Relative Timed Event Queues (RELTEQ), which provides an expressive set of primitives at a low processor and memory overhead. We then leveraged RELTEQ to create an efficient, modular and extensible design for enhancing a real-time operating system with periodic tasks, polling, idling periodic and deferrable servers, and a two-level fixed-priority Hierarchical Scheduling Framework (HSF). The HSF design provides temporal isolation and supports independent development of components by separating the global and local scheduling, and allowing each server to define a dedicated scheduler. Furthermore, the design addresses the system overheads inherent to an HSF and prevents undesirable interference between components. It limits the interference of inactive servers on the system level by means of wakeup events and a combination of inactive server queues with a stopwatch queue. Our implementation is modular and requires only a few modifications of the underlying operating system. We then investigated scalable components operating in a memory-constrained system. We first showed how to reduce the memory requirements in a streaming multimedia application, based on a particular priority assignment of the different components along the processing chain. Then we investigated adapting the resource provisions to tasks during runtime, referred to as mode changes. We presented a novel mode change protocol called Swift Mode Changes, which relies on Fixed Priority with Deferred preemption Scheduling to reduce the mode change latency bound compared to existing protocols based on Fixed Priority Preemptive Scheduling. We then presented a new partitioned parallel-task scheduling algorithm called Parallel-SRP (PSRP), which generalizes MSRP for multiprocessors, and the corresponding schedulability analysis for the problem of multi-resource scheduling of parallel tasks with real-time constraints. We showed that the algorithm is deadlock-free, derived a maximum bound on blocking, and used this bound as a basis for a schedulability test. We then demonstrated how PSRP can exploit the inherent parallelism of a platform comprised of multiple heterogeneous resources. Finally, we presented Grasp, which is a visualization toolset aiming to provide insight into the behavior of complex real-time systems. Its flexible plugin infrastructure allows for easy extension with custom visualization and analysis techniques for automatic trace verification. Its capabilities include the visualization of hierarchical multiprocessor systems, including partitioned and global multiprocessor scheduling with migrating tasks and jobs, communication between jobs via shared memory and message passing, and hierarchical scheduling in combination with multiprocessor scheduling. For tracing distributed systems with asynchronous local clocks Grasp also supports the synchronization of traces from different processors during the visualization and analysis

Integrated System Architectures for High-Performance Internet Servers

Ph.D.Computer Science and EngineeringUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/90845/1/binkert-thesis.pd

Um ambiente de suporte à execução de aplicações em redes de sensores sem fios

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Ciência da Computação.Em uma Rede de Sensores sem Fios, diversos nodos sensores obtém dados do local onde se encontram e comunicam-se entre si, para gerar uma visão global de um objeto de estudo. A idéia de uma rede auto-gerenciada de dispositivos autônomos, de baixa potência, que colete dados de um ambiente e propague informações através de um enlace sem fios traz uma série de novos desafios e requisitos de suporte à execução de aplicações. Diversos projetos de pesquisa se propuseram a tratar o problema de suporte de sistema para redes de sensores sem fios. Entretanto, a maioria deles falha em tratar principalmente dois dos requisitos levantados neste trabalho: configuração transparente do canal de comunicação e abstração unificada e eficiente de hardware de sensoriamento. Este trabalho apresenta o projeto e implementação de um ambiente de suporte à execução de aplicações em redes de sensores sem fios, baseado no sistema operacional EPOS, que inclui o projeto e implementação do protocolo de controle de acesso ao meio C-MAC (Configurable MAC) e um sistema de aquisição de dados de sensores. O projeto e implementação modular do protocolo C-MAC permitem que aplicações configurem o canal de comunicação de acordo com suas necessidades. O sistema de aquisição de dados de sensor desenvolvido é capaz de abstrair famílias de dispositivos sensores de maneira uniforme, sem ocasionar sobrecusto excessivo, e apresenta vantagens significativas com relação a outras soluções encontradas em outros sistemas operacionais para redes de sensores