5,413 research outputs found
Process algebra, process scheduling, and mutual exclusion
In the case of multi-threading as found in contemporary programming
languages, parallel processes are interleaved according to what is known as a
process-scheduling policy in the field of operating systems. In a previous
paper, we extend ACP with this form of interleaving. In the current paper, we
do so with the variant of ACP known as ACP. The choice of
ACP stems from the need to cover more process-scheduling policies.
We show that a process-scheduling policy supporting mutual exclusion of
critical subprocesses is now covered.Comment: 15 pages, there is noticeable text overlap with earlier papers
(arXiv:1912.10041, arXiv:1703.06822); 15 pages, Section 3.2 improved; 15
pages, minor improvements including replacement of reference at end Section
3.
Analysing Mutual Exclusion using Process Algebra with Signals
In contrast to common belief, the Calculus of Communicating Systems (CCS) and
similar process algebras lack the expressive power to accurately capture mutual
exclusion protocols without enriching the language with fairness assumptions.
Adding a fairness assumption to implement a mutual exclusion protocol seems
counter-intuitive. We employ a signalling operator, which can be combined with
CCS, or other process calculi, and show that this minimal extension is
expressive enough to model mutual exclusion: we confirm the correctness of
Peterson's mutual exclusion algorithm for two processes, as well as Lamport's
bakery algorithm, under reasonable assumptions on the underlying memory model.
The correctness of Peterson's algorithm for more than two processes requires
stronger, less realistic assumptions on the underlying memory model.Comment: In Proceedings EXPRESS/SOS 2017, arXiv:1709.0004
Separation of Circulating Tokens
Self-stabilizing distributed control is often modeled by token abstractions.
A system with a single token may implement mutual exclusion; a system with
multiple tokens may ensure that immediate neighbors do not simultaneously enjoy
a privilege. For a cyber-physical system, tokens may represent physical objects
whose movement is controlled. The problem studied in this paper is to ensure
that a synchronous system with m circulating tokens has at least d distance
between tokens. This problem is first considered in a ring where d is given
whilst m and the ring size n are unknown. The protocol solving this problem can
be uniform, with all processes running the same program, or it can be
non-uniform, with some processes acting only as token relays. The protocol for
this first problem is simple, and can be expressed with Petri net formalism. A
second problem is to maximize d when m is given, and n is unknown. For the
second problem, the paper presents a non-uniform protocol with a single
corrective process.Comment: 22 pages, 7 figures, epsf and pstricks in LaTe
A Time-Triggered Constraint-Based Calculus for Avionic Systems
The Integrated Modular Avionics (IMA) architec- ture and the Time-Triggered
Ethernet (TTEthernet) network have emerged as the key components of a typical
architecture model for recent civil aircrafts. We propose a real-time
constraint-based calculus targeted at the analysis of such concepts of avionic
embedded systems. We show our framework at work on the modelisation of both the
(IMA) architecture and the TTEthernet network, illustrating their behavior by
the well-known Flight Management System (FMS)
Tools for distributed application management
Distributed application management consists of monitoring and controlling an application as it executes in a distributed environment. It encompasses such activities as configuration, initialization, performance monitoring, resource scheduling, and failure response. The Meta system (a collection of tools for constructing distributed application management software) is described. Meta provides the mechanism, while the programmer specifies the policy for application management. The policy is manifested as a control program which is a soft real-time reactive program. The underlying application is instrumented with a variety of built-in and user-defined sensors and actuators. These define the interface between the control program and the application. The control program also has access to a database describing the structure of the application and the characteristics of its environment. Some of the more difficult problems for application management occur when preexisting, nondistributed programs are integrated into a distributed application for which they may not have been intended. Meta allows management functions to be retrofitted to such programs with a minimum of effort
Modelling Mutual Exclusion in a Process Algebra with Time-outs
I show that in a standard process algebra extended with time-outs one can
correctly model mutual exclusion in such a way that starvation-freedom holds
without assuming fairness or justness, even when one makes the problem more
challenging by assuming memory accesses to be atomic. This can be achieved only
when dropping the requirement of speed independence.Comment: arXiv admin note: text overlap with arXiv:2008.1335
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