Encontrados 35 documentos, a visualizar página 1 de 4
A feedback-based decentralised coordination model for distributed open real-tim...
Nogueira, Luis; Pinho, Luis Miguel; Coelho, JorgeMoving towards autonomous operation and management of increasingly complex open distributed real-time systems poses very significant challenges. This is particularly true when reaction to events must be done in a timely and predictable manner while guaranteeing Quality of Service (QoS) constraints imposed by users, the environment, or applications. In these scenarios, the system should be able to maintain a glo...
Real-time scheduling of parallel tasks in the Linux Kernel
Fonseca, José; Nogueira, Luis; Maia, Cláudio; Pinho, Luis MiguelThis paper proposes a global multiprocessor scheduling algorithm for the Linux kernel that combines the global EDF scheduler with a priority-aware work-stealing load balancing scheme, enabling parallel real-time tasks to be executed on more than one processor at a given time instant. We state that some priority inversion may actually be acceptable, provided it helps reduce contention, communication, synchronisa...
Supporting real-time parallel task models with work-stealing
Maia, Cláudio; Nogueira, Luis; Pinho, Luis MiguelDynamic parallel scheduling using work-stealing has gained popularity in academia and industry for its good performance, ease of implementation and theoretical bounds on space and time. Cores treat their own double-ended queues (deques) as a stack, pushing and popping threads from the bottom, but treat the deque of another randomly selected busy core as a queue, stealing threads only from the top, whenever they...
Dynamic global scheduling of parallel real-time tasks
Nogueira, Luis; Fonseca, José; Maia, Cláudio; Pinho, Luis MiguelHigh-level parallel languages offer a simple way for application programmers to specify parallelism in a form that easily scales with problem size, leaving the scheduling of the tasks onto processors to be performed at runtime. Therefore, if the underlying system cannot efficiently execute those applications on the available cores, the benefits will be lost. In this paper, we consider how to schedule highly het...
Server-based scheduling of parallel real-time tasks
Nogueira, Luis; Pinho, Luis MiguelMulticore platforms have transformed parallelism into a main concern. Parallel programming models are being put forward to provide a better approach for application programmers to expose the opportunities for parallelism by pointing out potentially parallel regions within tasks, leaving the actual and dynamic scheduling of these regions onto processors to be performed at runtime, exploiting the maximum amount o...
A framework for offloading real-time applications in a distributed environment
Maia, Cláudio; Silva, Guilherme; Ferreira, Luis; Pinho, Luis Miguel; Nogueira, Luis; Gonçalves, JoelThis work focuses on highly dynamic distributed systems with Quality of Service (QoS) constraints (most importantly real-time constraints). To that purpose, real-time applications may benefit from code offloading techniques, so that parts of the application can be offloaded and executed, as services, by neighbour nodes, which are willing to cooperate in such computations. These applications explicitly state the...
On the use of code mobility mechanisms in real-time systems
Ferreira, Luis; Nogueira, LuisApplications with soft real-time requirements can benefit from code mobility mechanisms, as long as those mechanisms support the timing and Quality of Service requirements of applications. In this paper, a generic model for code mobility mechanisms is presented. The proposed model gives system designers the necessary tools to perform a statistical timing analysis on the execution of the mobility mechanisms t...
Evaluating Android OS for embedded real-time systems
Maia, Cláudio; Nogueira, Luis; Pinho, Luis MiguelSince its official public release, Android has captured the interest from companies, developers and the general audience. From that time up to now, this software platform has been constantly improved either in terms of features or supported hardware and, at the same time, extended to new types of devices different from the originally intended mobile ones. However, there is a feature that has not been explored y...
Supporting parallelism in server-based multiprocessor systems
Nogueira, Luis; Pinho, Luis MiguelDeveloping an efficient server-based real-time scheduling solution that supports dynamic task-level parallelism is now relevant to even the desktop and embedded domains and no longer only to the high performance computing market niche. This paper proposes a novel approach that combines the constantbandwidth server abstraction with a work-stealing load balancing scheme which, while ensuring isolation among tasks...
Flexible and dynamic replication control for interdependent distributed real-ti...
Nogueira, Luis; Pinho, Luis Miguel; Coelho, JorgeReplication is a proven concept for increasing the availability of distributed systems. However, actively replicating every software component in distributed embedded systems may not be a feasible approach. Not only the available resources are often limited, but also the imposed overhead could significantly degrade the system’s performance. This paper proposes heuristics to dynamically determine which component...
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