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Publicações

Publicações por HumanISE

2013

Are virtual channels the bottleneck of priority-aware wormhole-switched NoC-based many-cores?

Autores
Nikolic, B; Ali, HI; Petters, SM; Pinho, LM;

Publicação
RTNS

Abstract
Preemptions via virtual channels have been proposed as a means to introduce the notion of priorities and real-time concepts in wormhole-switched NoC-based architectures. This work presents a holistic approach, which utilises a novel three-staged mapping method in order to assess what should be the physical characteristics of the platform (and its interconnect), such that real-time guarantees can be provided, assuming a given workload. We estimate the "gap" between platform characteristics required for the real-time analysis and those of currently available many-core platforms and propose to employ the existing feature of many-core platforms in order to significantly reduce this gap. The experiments demonstrate that virtual channels, an essential prerequisite for the real-time analysis, are not the bottle-neck. The approach presented in this paper can help system designers to select/design the most suitable platform for a given workload, such that all temporal constraints are met and over-dimensioning is avoided. © 2013 ACM.

2013

Real-time programming on accelerator many-core processors

Autores
Michell, S; Moore, B; Pinho, LM;

Publicação
HILT

Abstract
Multi-core platforms are challenging the way software is developed, in all application domains. For the particular case of real-time systems, models for the development of parallel software must be able to be shown correct in both functional and non-functional properties at design-time. In particular, issues such as concurrency, timing behaviour and interaction with the environment need to be addressed with the same caution as for the functional requirements. This paper proposes an execution model for the parallelization of real-time software, based upon a fine-grained parallelism support being proposed to Ada, a programming language particularly suited to the development of critical, concurrent software. We also show the correctness of the proposed model in terms of satisfying constraints related to execution order and unbounded priority inversions. © 2013 ACM.

2013

Scheduling Parallel Real-Time Tasks using a Fixed-Priority Work-Stealing Algorithm on Multiprocessors

Autores
Maia, C; Nogueira, L; Pinho, LM;

Publicação
2018 8TH IEEE INTERNATIONAL SYMPOSIUM ON INDUSTRIAL EMBEDDED SYSTEMS (SIES)

Abstract
This paper proposes a model for scheduling parallel real-time tasks. The proposed model uses a work-stealing approach to schedule real-time parallel task sets at runtime, where each job may present a nested fork-join structure, generate an arbitrary number of parallel jobs, and each parallel job inherits the timing properties of the job that spawns it.

2013

Tasklettes - A Fine Grained Parallelism for Ada on Multicores

Autores
Michell, S; Moore, B; Pinho, LM;

Publicação
Ada-Europe

Abstract
The widespread use of multi-CPU computers is challenging programming languages, which need to adapt to be able to express potential parallelism at the language level. In this paper we propose a new model for fine grained parallelism in Ada, putting forward a syntax based on aspects, and the corresponding semantics to integrate this model with the existing Ada tasking capabilities. We also propose a standard interface and show how it can be extended by the user or library writers to implement their own parallelization strategies. © 2013 Springer-Verlag.

2013

Editorial

Autores
Pinho, LM;

Publicação
Ada User Journal

Abstract

2013

Session summary: Multiprocessor issues, Part 2 (resource control protocols)

Autores
Wellings, A; Pinho, LM;

Publicação
Ada User Journal

Abstract
The second session on the topic of Multiprocessor Issues reviewed and evaluated the efficacy of the Ada 2012 support in the area of multiprocessor resource control. Andy Wellings, the Chair presented a proposal of an API that allowed controlling and extending the queue locks, and implementing the access control protocols. In the second part of the session, Miguel Pinho started by presenting an overview of Transactional Memory (TM), providing a quick overview of how in this approach atomic sections are executed concurrently and speculatively, in isolation. In the third topic of the session, the Chair started by providing an overview of the Reference Manual wordings concerning the access and control protocols for Protected Objects, noting that both the RM and the Annotated Reference Manual (ARM) do not fully define the access protocol for a protected object on a multiprocessor system. Finally, in the last topic (parallel barriers in Protected Objects), the workshop concluded that this would be a good mechanism to have, but that a suitable approach needs further investigation.

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