Computation-communication overlap techniques for parallel spectral calculations in gyrokinetic Vlasov simulations
ジャイロ運動論的シミュレーションにおける並列スペクトル法計算に対する演算と通信のオーバーラップ手法
前山 伸也; 渡邉 智彦*; 井戸村 泰宏
; 仲田 資季; 沼波 政倫*; 石澤 明宏*
Maeyama, Shinya; Watanabe, Tomohiko*; Idomura, Yasuhiro; Nakata, Motoki; Nunami, Masanori*; Ishizawa, Akihiro*
We extend our gyrokinetic Vlasov simulation code GKV to run efficiently on peta-scale supercomputers. A key numerical technique is the parallel Fast Fourier Transform (FFT) required for parallel spectral calculations, where masking of the cost of inter-node transpose communications is essential to improve strong scaling. To mask communication costs, computation-communication overlap techniques are applied for FFTs and transpose with the help of the hybrid parallelization of message passing interface and open multi-processing. Integrated overlaps including whole spectral calculation procedures show better scaling than simple overlaps of FFTs and transpose. The masking of communication costs significantly improves strong scaling of the GKV code, and makes substantial speed-up toward multi-scale turbulence simulations.