López Navarro, Juan Manuel and Alves, Diogo and Neto, C. A. and Valcárcel, D.F. and Felton, R. and Barbalace, A. and Boncagni, L. and Card, P. and Tommasi, G. de and Goodyear, A. and Jachmich, S. and Lomas, P.J. and Maviglia, F. and McCullen, P. and Murari, A. and Rainford, M. and Reux, C. and Rimini, F. and Sartori, F. and Stephen, A.V. and Vega, J. and Vitelli, R. and Zabeo, L. and Zastrow, K.D.
A new generation of real-time systems in the JET tokamak.
In: "18th Real-Time Conference, June 11-15, 2012, Berkeley, CA", 11/06/2012 - 15/06/2012, Berkeley, CA. ISBN 978-1-4673-1082-6. pp. 1-9.
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 the 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 realtime 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 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 multicore architectures. In the past year, four new systems based on this philosophy have been installed and are now part of the JET’s routine operation. The focus of the present work is on the configuration and interconnection of the ingredients that enable these new systems’ real-time capability and on the impact that JET’s distributed real-time architecture has on system engineering requirements, such as algorithm testing and plant commissioning. Details are given about the common real-time configuration and development path 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 synchronising 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.