Ready, Thready, Go: Exploiting MPI + OpenMP in Operational Weather Forecasting
Presenter
Event Type
Minisymposium
Emerging Application Domains
Climate and Weather
Life Sciences
TimeThursday, 13 June 201917:15 - 17:45
LocationHG D 3.2
DescriptionDr. Paul Selwood will discuss how accurate weather forecasts are hugely important to a nation’s economy. They help keep transport links open, keep electricity flowing and enable emergency response to extreme weather events. The Unified Model is a key component in the Met Office’s ability to generate hundreds of forecasts every day to tight operational timescales. It is constantly being improved with more accurate and computationally expensive physics. MPI + OpenMP has been an important tool in meeting the scalability challenge this has presented. The Unified Model has had a long journey with parallelism, from autotasking on Cray vector systems, through being a MPI-only parallel model and latterly to an MPI + OpenMP hybrid one. In doing so it has been able to adapt to over 20 years of different supercomputer architectures. MPI + OpenMP has enabled the use of hyperthreads, been key to a number of I/O accelerations, has allowed experimentation with dynamic load balancing and has become a fully-fledged part of the model’s parallelisation strategy. This presentation will share this journey (there is far more than simple !OMP PARALLEL DO) along with lessons learned along the way.