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Safety-critical systems require certification in order to attain permission to operate. Nowadays, these systems routinely embed a communication sub-systems whose performance must be formally verified for certification. Deterministic Network Calculus (DNC) can be employed for this task. It provides a mathematical framework to derive worst-case bounds on the delay of data flows, i.e., deterministic...
Messages traversing a network commonly experience waiting times due to sharing the forwarding resources. During those times, the crossed systems must provide sufficient buffer space for queueing messages. Network Calculus (NC) is a mathematical methodology for bounding flow delays and system buffer requirements. The accuracy of these performance bounds depends mainly on two factors: the principles...
A NoC-based system subject to real-time constraints requires hard bounds on end-to-end data transfer latencies. Regulating the channel injection rates solves the problem by suppressing link congestion and router queue saturation, provided that the channel rates guarantee fairness in the data distribution. We propose a distributed algorithm for the computation of a channel rate vector solution, suitable...
We propose an integrated development environment (IDE) for developing formulae written in the multiple ambient calculus (MAC). MAC is a kind of process algebra designed for modeling freight systems in which a lot of containers are transported by several vessels from one port to another port via several hub ports. We have been studying a handling management system that confirms the validity of container...
Microservices is an architectural style inspired by service-oriented computing that has recently started gainingpopularity. Jolie is a programming language based on the microservices paradigm: the main building block of Jolie systems are services, in contrast to, e.g., functions or objects. The primitives offered by the Jolie language elicit many of the recurring patterns found in microservices, like...
Backlog bound analysis is crucial for predicting buffer sizing boundary in on-chip virtual-channel routers. However, the complicated resource contention among traffic flows makes the analysis difficult. Because conventional simulation-based approaches are generally incapable of investigating the worst-case scenarios for the backlog bounds, we propose a formal analysis technique. We identify basic...
Studies of multi-server networks are usually conducted on the assumptions of independent servers and specific arrivals, which may not capture the characteristics of realistic networks. In this paper, we propose a novel stochastic network calculus approach to perform delay analysis for a general multi-server network. The stochastic network service curves are derived in two ways with different assumptions...
The AFDX technology is used as backbone in several aircraft. It offers a high bandwidth (commonly 100Mb/s), and guaranteed per data flow a bound on the network traversal delay, while being a shared resource. To do so, it uses a segregation mechanism, the Virtual Link (VL), designed as a bus abstraction.
We propose stochastic performance analysis in order to provide probabilistic quality-of-service guarantees in on-chip packet-switching networks. In contrast to deterministic analysis which gives per-flow absolute delay bound, stochastic analysis derives per-flow probabilistic delay bounding function, which can be used to avoid over-dimensioning network resources. Based on stochastic network calculus,...
Multiplexing models are common in resource sharing communication media such as buses, crossbars and networks. While sending packets over a multiplexing node, the packet delay bound can be computed using network calculus models. The tightness of such delay bound remains an open problem. This paper studies the multiplexing models for weighted round robin scheduling with different traffic arrival curves,...
A packet-switched network node with constant capacity (in bps) is considered, where packets within each flow are served in the first in first out (FIFO) manner. While this single node system is perhaps the simplest computer communication system, its stochastic service curve characterization and independent case analysis in the context of stochastic network calculus (snetcal) are still basic and many...
Network calculus is a powerful methodology of characterizing queueing processes and has wide applications. In this work1, we focus on the fundamental problem of “under what condition can we derive stable backlog bounds using the current state of art of stochastic network calculus”. We model an network element (called a “node” here) as a single server with impairment service based on two best-known...
A fundamental problem for the delay and backlog analysis across multi-hop paths in wireless networks is how to account for the random properties of the wireless channel. Since the usual statistical models for radio signals in a propagation environment do not lend themselves easily to a description of the available service rate, the performance analysis of wireless networks has resorted to higher-layer...
Optical networks have recently been proposed for chip-scale communication on high performance manycore chips by leveraging their notable advantages in bandwidth and power-efficiency. The design of optical network on-chip (NoC) is characterized by challenging trade-offs among latency, throughput, energy consumption, and silicon area requirements. These trade-offs are conventionally studied using simulations...
This work addresses the applicability of a switched queuing network as the sole communication network in an aircraft cabin, and proposes an algorithm based on a mixed-integer program to determine hard bounds for the end-to-end delay. These hard bounds guarantee mandatory performance bounds for safety-relevant functions in the aircraft cabin, such as audio announcements or smoke detection. Techniques...
GPS is an ideal well known policy designed to share the capacity of a server between the input flows: each flow receives a fractional part, defined by the administrator, of the total server capacity1. It has several practical implementations, like P-GPS. These policies have been defined in the context of a constant-rate server. In this paper, a generalisation of GPS and P-GPS is proposed, in network...
The untyped aspect calculus provides direct support for aspects and other related constructs of aspect-oriented programming languages. The calculus uses object and aspect rather than function as its primitive constructs and define operations on these primitives directly. In this paper, we present how the untyped aspect calculus, a minimal language representing the essence of the class of aspect-oriented...
The π-calculus is a process algebra originally designed for modelling communicating systems. In this work, it is applied to the design of schedules for partial dynamic reconfiguration, which denote when modules become active and which channels they use for communication. While the execution of the π-calculus in software is possible, a direct execution in hardware is desirable for two reasons: Firstly,...
Several memory architectures have been proposed to enable TLS in multi-core system. Each has its own data dependence violation mechanism and speculative thread restart policy. And most of them use a global component to check data dependence violation. No analytical model has been proposed to compare the impact of different memory architectures on thread restarts and the global component processing...
The event calculus is a logic-based formalism for dealing with temporal reasoning concerns. Erlang is a functional programming language designed from the ground up for tackling distributed programming problems. In this paper, it is shown that the event calculus is a suitable tool for designing and analyzing distributed systems written as Erlang programs.
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