Performance Evaluation of Quantum ESPRESSO on NEC SX-ACE

In recent years, a lot of computer simulation codes have been developed as open-source software. Meanwhile major processors adopt a concept of a vector processing in high performance computing. Hence, the computer simulation codes need to follow a vector processing manner to have a benefit of a computational potential of the vector processing. Our study is evaluation and analysis of performance of various simulation codes developed as open-source software on several vector architectures. In this paper, we evaluate one package of Quantum ESPRESSO as an open-source software code in materials science. Quantum ESPRESSO makes use of several numerical libraries and it is known that parallel parameters called parallelization levels affect the performance in parallel execution. We discuss adjustability of the code to a vector architecture. Moreover, we clarify that the performance of PWscf, which is one of major packages of Quantum ESPRESSO, depends on numerical libraries and parallelization levels of PWscf. For evaluation of performance, we use a vector-parallel supercomputer system named NEC SX-ACE and an Intel Xeon-based cluster system named NEC LX 406Re-2. From this evaluation, we confirm that the code is suitable for vector architectures. Additionally, we clarify the effectiveness of applying optimum numerical libraries to each architecture with appropriate parallel parameters to obtain the high performance.