The Earth Sciences Department of the Barcelona Supercomputing Center (BSC) is working on the development of a new chemical weather forecasting system based on the NCEP/NMMB multi-scale meteorological model. We present our efforts on porting and optimizing the NMMB/BSC-CTM model. The purpose is to prepare the model for large scale experiments and increase the resolution of the executed domain. The programming model OmpSs, which is developed at BSC-CNS, enables asynchronous parallelism by the use of data-dependencies between the different tasks and is built on top of Mercurium compiler and Nanos++ runtime system.
Through this work we describe how we used this programming model to improve computation functions by creating tasks, using threads, and parallelize significant computation loops only. Moreover, we use OmpSs to overlap communication with computation which is crucial as in the future we expect to scale our application on thousands cores. There is the need to refactor part of the code because of reentrancy issues. For all the results we use the well established tools Extrae/Paraver to instrument, visualize and understand various performance issues. We present the preliminary results and our efforts of porting the model in order to help other scientists to port their applications by using OmpSs.
