scholarly journals Cooperative and Non-Cooperative Frameworks with Utility Function Design for Intermediate Deadline Assignment in Real-Time Distributed Systems

Mathematics ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1579
Author(s):  
Jinkyu Lee

In real-time distributed systems, it is important to provide offline guarantee for an upper-bound of each real-time task’s end-to-end delay, which has been achieved by assigning proper intermediate deadlines of individual real-time tasks at each node. Although existing studies have succeeded to utilize mathematical theories of distributed computation/control for intermediate deadline assignment, they have assumed that every task operates in a cooperative manner, which does not always hold for real-worlds. In addition, existing studies have not addressed how to exploit a trade-off between end-to-end delay fairness among real-time tasks and performance for minimizing aggregate end-to-end delays. In this paper, we recapitulate an existing cooperative distributed framework, and propose a non-cooperate distributed framework that can operate even with selfish tasks, each of which is only interested in minimizing its own end-to-end delay regardless of achieving the system goal. We then propose how to design utility functions that allow the real-time distributed system to exploit the trade-off. Finally, we demonstrate the validity of the cooperative and non-cooperative frameworks along with the designed utility functions, via simulations.

2021 ◽  
Vol 40 (2) ◽  
pp. 65-69
Author(s):  
Richard Wai

Modern day cloud native applications have become broadly representative of distributed systems in the wild. However, unlike traditional distributed system models with conceptually static designs, cloud-native systems emphasize dynamic scaling and on-line iteration (CI/CD). Cloud-native systems tend to be architected around a networked collection of distinct programs ("microservices") that can be added, removed, and updated in real-time. Typically, distinct containerized programs constitute individual microservices that then communicate among the larger distributed application through heavy-weight protocols. Common communication stacks exchange JSON or XML objects over HTTP, via TCP/TLS, and incur significant overhead, particularly when using small size message sizes. Additionally, interpreted/JIT/VM-based languages such as Javascript (NodeJS/Deno), Java, and Python are dominant in modern microservice programs. These language technologies, along with the high-overhead messaging, can impose superlinear cost increases (hardware demands) on scale-out, particularly towards hyperscale and/or with latency-sensitive workloads.


2015 ◽  
Vol 72 (5) ◽  
Author(s):  
Ahmed Abu-Khadrah ◽  
Zahriladha Zakaria ◽  
Mohdazlishah Othman

Nowadays supporting quality of service (QOS) for real time application is the main challenge of the wireless area network. 802.11standards use distributed Coordination Function (DCF) protocol and Enhanced Distributed Channel Access (EDCA) protocol in the MAC layer. DCF protocol has only one queue for different data types, it deals with data depending on the arriving time. There is no priority to serve real time applications faster. However EDCA protocol has four queues and each queue works with specific data type. Voice, video, best effort and background are the different queues in the EDCA protocol. Different parameters and priorities are defined for each queue. The voice queue reserves the highest priority and serves its data first. In this paper QOS parameters are measured for both DCF and EDCA protocol by using OPNET simulation. The QOS parameters must reach the requirements to support QOS. The results show how QOS parameters do not reach the requirements when using DCF protocol. The values of the end to end delay and the packet loss percentage are 0.514second, 19.04% respectively. But, when using EDCA protocol the end to end delay becomes 0.0624 second and the percentage of the packet loss decreases until reach 0.00617%. So the QOS parameters achieve requirements with EDCA protocol and support QOS.


2008 ◽  
Vol 2008 ◽  
pp. 1-16 ◽  
Author(s):  
Liang Song ◽  
Dimitrios Hatzinakos

There is an emerging need for realizing real-time quality of service (QoS) over multihop wireless communications in large-scale wireless networks. The applications can include wireless mesh infrastructure for broadband Internet access supporting multimedia services, visual sensor networks for surveillance, and disaster-relief networks. However, a number of challenges still exist as revealed by recent works, where the dataflow QoS performance such as throughput and end-to-end delay can degrade fast with the number of wireless hops. We propose to use large-scale cognitive networking methods to resolve the wireless multihop challenges. By the cognitive-networking concept, data packets travel along opportunistically available paths in the network with opportunistically available spectrum in every hop. Reliable end-to-end communications can be achieved for real-time services, where we show that (1) dataflow throughput can be independent of any number of wireless hops, (2) end-to-end delay and delay variance increase linearly with the number of wireless hops, and (3) delay variance decreases to zero with higher network density. These results are supported by analysis, simulations, and experiments.


Author(s):  
Wonseok Jang ◽  
Hansaem Jeong ◽  
Kyungtae Kang ◽  
Nikil Dutt ◽  
Jong-Chan Kim

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