Treffer: An OpenMP free agent threads implementation

In this paper, we introduce a design and implementation of the free agent threads for OpenMP. These threads increase the malleability of the OpenMP programming model, offering resource managers and runtime systems flexibility to manage threads and resources efficiently. We demonstrate how free agent threads can address load imbalances problems at the OpenMP level and at an MPI level or higher. We use two mini-apps extracted from two real HPC applications and representative of real-world codes to demonstrate this. We conclude that more malleability in thread management is necessary, and free agents can be regarded as a practical starting point to increase malleability in thread management. ; This work has been done as part of the European Processor Initiative project. The European Processor Initiative (EPI) (FPA: 800928) has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement EPI-SGA1: 826647. It has also received funding from the European Union's Horizon 2020/EuroHPC research and innovation programme under grant agreement No 955606 (DEEP-SEA); and the support of the Spanish Ministry of Science and Innovation (Computacion de Altas Prestaciones VIII: PID2019-107255GB). ; Peer Reviewed ; Postprint (author's final draft)