Development of a Scalable Data Exchange Interface for Fast Parallel I/O within the Integrated Tokamak Modelling Framework


The EFDA Task Force ITM (Integrated Tokamak Modelling) aims at creating a global modelling framework for the International Thermonuclear Experimental Reactor (ITER) currently under construction in Cadarache (France). For this purpose, various codes used to model key physical processes within the core plasma and its interaction with the vessel walls will be coupled together via the KEPLER workflow system.

Many of these codes are already parallelized to decrease their time to solution. However, this implies that an effective data exchange between two or more codes has to be provided allowing simulation results of one code to be efficiently transferred to the next. Currently the data exchange mechanism works only in a serial way, such that the participating processes of one code first have to gather their simulation data and transfer it serially to the next code. This can lead to serious potential bottlenecks at the interface between the codes.

To optimize the data transfer between the models, it is proposed to parallelize the data exchange mechanism as well. As a first example two ITM kinetic edge modelling codes with different foci, ERO and B2-EIRENE, will be used to demonstrate the advantages of parallel data exchange.

KEPLER uses a data exchange library called UAL (Universal Access Layer) for I/O operations between codes and stores simulation results in a large database for further use. Codes within KEPLER retrieve and store data by calling the UAL. The data itself is structured in so-called CPOs (Consistent Physical Objects). The outcome of this work will be an interface or library that allows parallel codes to utilize all of their processes for input and output operations. This is expected to significantly improve the performance between interacting codes and eliminate the bottlenecks caused by serial I/O.


Forschungszentrum Jülich - JSC - Simulation and Data Laboratory Plasma Physics

German Research School for Simulation Sciences - Laboratory for Parallel Programmingon Sciences

Associated Partners

Forschungszentrum Jülich - IEF-4 (Plasma Physics)

EFDA Task Force on Integrated Tokamak Modelling (ITM)


JARA - Jülich Aachen Research Alliance

Last Modified: 08.05.2023