The design, implementation and evaluation of SMART: a scheduler for multimedia applications
Proceedings of the sixteenth ACM symposium on Operating systems principles
Resource kernels: a resource-centric approach to real-time and multimedia systems
Readings in multimedia computing and networking
Internet QoS: Architectures and Mechanisms for Quality of Service
Internet QoS: Architectures and Mechanisms for Quality of Service
Towards Compositionality in Real-Time Resource Partitioning Based on Regularity Bounds
RTSS '01 Proceedings of the 22nd IEEE Real-Time Systems Symposium
Low-Latency Hard Real-Time Communication over Switched Ethernet
ECRTS '04 Proceedings of the 16th Euromicro Conference on Real-Time Systems
FSF: A Real-Time Scheduling Architecture Framework
RTAS '06 Proceedings of the 12th IEEE Real-Time and Embedded Technology and Applications Symposium
An analysis method for variable execution time tasks based on histograms
Real-Time Systems
RT-EP: a fixed-priority real time communication protocol over standard ethernet
Ada-Europe'05 Proceedings of the 10th Ada-Europe international conference on Reliable Software Technologies
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Switched Ethernet is being used for real time transmissions in industrial automation more and and more. Most modern industrial switches are equipped with mechanisms to deal with time predictability. However, real-time transmission not only requires these mechanisms, but also the proper policies for managing network resources. This paper proposes the use of contracts. A contract is a set of transmission specifications which are negotiated between the applications and the run-time support. They define the application workload and the required performance guarantees. We implement contracts for real-time streaming as an extension of FRESCOR (Framework for Real-time Embedded Systems based on COntRacts). This framework was initially thought for providing deterministic performance guarantees to strictly periodic workloads. This work extends it by using the concept of Classes Of Service (CoS) to deal with a wider range of workloads and guarantees and, particularly, with the transmission of highly variable bit rate (VBR) streams, like video. CoS enables, for example, joint transmission of real-time periodic workloads and VBR streams. CoS are implemented using a combination of resource reservation and resource preallocation techniques. The packet scheduling facilities of managed switches and Linux are shown to be key for managing network resources. Evaluations about the effectiveness of the extended FRESCOR framework and the feasibility of using Switched Ethernet in real-time industrial environments are also presented.