Search results for "Concurrency"

Distributed Computing on Distributed Memory

2018

Distributed computation is formalized in several description languages for computation, as e.g. Unified Modeling Language (UML), Specification and Description Language (SDL), and Concurrent Abstract State Machines (CASM). All these languages focus on the distribution of computation, which is somewhat the same as concurrent computation. In addition, there is also the aspect of distribution of state, which is often neglected. Distribution of state is most commonly represented by communication between active agents. This paper argues that it is desirable to abstract from the communication and to consider abstract distributed state. This includes semantic handling of conflict resolution, e.g. i…

C<sup>2</sup>SMA/CA: Enabling co-channel concurrency in WLANs using positional information

2013

An attractive approach to overcome capacity limitations in a densely deployed WLAN environment is to enable transmission concurrency. In this paper, we propose a co-channel concurrent transmission scheme, referred to as C2SMA/CA, which determines whether to allow multiple concurrent transmissions based on interference estimation using positional information. A distributed multi-link concurrency scheduling algorithm is implemented, and its performance is evaluated through extensive simulations.

FPGA-based concurrent watchdog for real-time control systems

2003

A straightforward and efficient implementation of a custom concurrent watchdog processor for real-time control systems is presented. Emphasis is given to the techniques used for on-line checking the main processor activity without adding overhead, and to the advantages of a field programmable gate array implementation.

Simulation is decidable for one-counter nets

1998

We prove that the simulation preorder is decidable for the class of one-counter nets. A one-counter net consists of a finite-state machine operating on a variable (counter) which ranges over the natural numbers. Each transition can increase or decrease the value of the counter. A transition may not be performed if this implies that the value of the counter becomes negative. The class of one-counter nets is computationally equivalent to the class of Petri nets with one unbounded place, and to the class of pushdown automata where the stack alphabet is restricted to one symbol. To our knowledge, this is the first result in the literature which gives a positive answer to the decidability of sim…

A recognize-and-accuse policy to speed up distributed processes

1994

Data management and concurrency control in broadcast based asymmetric environments

2006

Masteroppgave i informasjons- og kommunikasjonsteknologi 2006 - Høgskolen i Agder, Grimstad Tens of millions of users have personal handheld devices with several network interfaces built-in, and the number of users and of network interfaces included are only increasing. This growth suggests a need for new methods to disseminate data to multiple clients, and cyclic broadcast is one approach. We do a survey on the various data management protocols that describe how to broadcast the data, and the concurrency control protocols that make sure all access to the database is consistent. The various data management and concurrency control techniques deals with the restrictions in asymmetric broadcas…

Improving Collective I/O Performance Using Non-volatile Memory Devices

2016

Collective I/O is a parallel I/O technique designed to deliver high performance data access to scientific applications running on high-end computing clusters. In collective I/O, write performance is highly dependent upon the storage system response time and limited by the slowest writer. The storage system response time in conjunction with the need for global synchronisation, required during every round of data exchange and write, severely impacts collective I/O performance. Future Exascale systems will have an increasing number of processor cores, while the number of storage servers will remain relatively small. Therefore, the storage system concurrency level will further increase, worseni…

CASE tool support for co-operative work in information systems design

1998

The need for asynchronous co-operative work in design is shown by many surveys of CASE tool use and research on design. MetaEdit+ is a metaCASE environment that allows multiple simultaneous modellers to work together on designing information systems and also information systems design methods. We describe the automatic locking strategies that enable MetaEdit+ to offer a high level of concurrency whilst guaranteeing consistency, enabling effective co-operative work. In particular we describe a new collection data structure that allows high concurrency of updates even at small sizes, fulfilling the need in CASE for largest growth of design information at the start of a project. Finally, we ev…

Verification of Well-Formed Communicating Recursive State Machines

2008

AbstractIn this paper we introduce a new (non-Turing equivalent) formal model of recursive concurrent programs called well-formed communicating recursive state machines (CRSM). CRSM extend recursive state machines (RSM) by allowing a restricted form of concurrency: a state of a module can be refined into a finite collection of modules (working in parallel) in a potentially recursive manner. Communication is only possible between the activations of modules invoked on the same fork. We study the model-checking problem of CRSM with respect to specifications expressed in a temporal logic that extends CaRet with a parallel operator (ConCaRet). We propose a decision algorithm that runs in time ex…

A Medium Level Language for Pyramid Architectures

1989

In the paper a Parallel C Languages for pyramid architectures is described. The concept of context is introduced in order to handle concurrence between processes in massive parallel machines. Feature implementation on the PAPIA-machine are given.