Parallel computational steering and analysis for HPC applications using a paraview interface and the HDF5 DSM virtual file driver

We present a framework for interfacing an arbitrary HPC simulation code with an interactive ParaView session using the HDF5 parallel IO library as the API. The implementation allows a flexible combination of parallel simulation, concurrent parallel analysis and GUI client, all of which may be on the same or separate machines. Data transfer between the simulation and the ParaView server takes place using a virtual file driver for HDF5 that bypasses the disk entirely and instead communicates directly between the coupled applications in parallel. The simulation and ParaView tasks run as separate MPI jobs and may therefore use different core counts and/or hardware configurations/platforms, making it possible to carefully tailor the amount of resources dedicated to each part of the workload. The coupled applications write and read datasets to the shared virtual HDF5 file layer, which allows the user to read data representing any aspect of the simulation and modify it using ParaView pipelines, then write it back, to be reread by the simulation (or vice versa). This allows not only simple parameter changes, but complete remeshing of grids, or operations involving regeneration of field values over the entire domain, to be carried out. To avoid the problem of manually customizing the GUI for each application that is to be steered, we make use of XML templates that describe outputs from the simulation, inputs back to it, and what user interactions are permitted on the controlled elements. This XML is used to generate GUI and 3D controls for manipulation of the simulation without requiring explicit knowledge of the underlying model.