An asynchronous writing method for restart files in the gysela code in prevision of exascale systems
Olivier Thomine, Julien Bigot, V. Grandgirard, Guillaume Latu, C. Passeron, Fabien Rozar · ESAIM Proceedings · 2013
The present work deals with an optimization procedure developed in the full-f global GYrokinetic SEmi-LAgrangian code (GYSELA). Optimizing the writing of the restart files is necessary to reduce the computing impact of crashes. These files require a very large memory space, and particularly so for very large mesh sizes. The limited bandwidth of the data pipe between the comput- ing nodes and the storage system induces a non-scalable part in the GYSELA code, which increases with the mesh size. Indeed the transfer time of RAM to data depends linearly on the files size. The necessity of non synchronized writing-in-file procedure is therefore crucial.