A New Generation of Real-Time Systems in the JET Tokamak

Diogo Alves, Andre C. Neto, Daniel F. Valcárcel, Robert Felton, Juan M. López, Antonio Barbalace, Luca Boncagni, Peter Card, Gianmaria De Tommasi, Alex Goodyear, Stefan Jachmich, Peter J. Lomas, Francesco Maviglia, Paul McCullen, Andrea Murari, Mark Rainford, Cedric Reux, Fernanda Rimini, Filippo Sartori, Adam V. StephenJesus Vega, Riccardo Vitelli, Luca Zabeo, Klaus-Dieter Zastrow

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Recently, a new recipe for developing and deploying real-time systems has become increasingly adopted in the JET tokamak. Powered by the advent of x86 multi-core technology and the reliability of JET’s well established Real-Time Data Network (RTDN) to handle all real-time I/O, an official Linux vanilla kernel has been demonstrated to be able to provide real-time performance to user-space applications that are required to meet stringent timing constraints. In particular, a careful rearrangement of the Interrupt ReQuests’ (IRQs) affinities together with the kernel’s CPU isolation mechanism allows one to obtain either soft or hard real-time behavior depending on the synchronization mechanism adopted. Finally, the Multithreaded Application Real-Time executor (MARTe) framework is used for building applications particularly optimised for exploring multi-core architectures. In the past year, four new systems based on this philosophy have been installed and are now part of JET’s routine operation. The focus of the present work is on the configuration aspects that enable these new systems’ real-time capability. Details are given about the common real-time configuration of these systems, followed by a brief description of each system together with results regarding their real-time performance. A cycle time jitter analysis of a user-space MARTe based application synchronizing over a network is also presented. The goal is to compare its deterministic performance while running on a vanilla and on a Messaging Real time Grid (MRG) Linux kernel.
Original languageEnglish
Pages (from-to)711-719
Number of pages9
JournalIEEE Transactions on Nuclear Science
Issue number2
Publication statusPublished - 3 Apr 2014

Keywords / Materials (for Non-textual outputs)

  • high energy physics instrumentation computing
  • jitter
  • plasma toroidal confinement
  • real-time systems
  • synchronisation
  • Tokamak devices
  • JET tokamak
  • real-time system
  • multicore technology
  • real-time data network
  • RTDN
  • Linux vanilla kernel
  • user-space application
  • Interrupt ReQuests
  • CPU isolation mechanism
  • hard real-time behavior
  • synchronization mechanism
  • multithreaded application real-time executor
  • MARTe framework
  • cycle time jitter analysis
  • messaging real time grid Linux kernel
  • Real-time systems
  • Kernel
  • Linux
  • Jitter
  • Plasmas
  • Stress
  • Switches
  • nuclear fusion
  • real-time


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