11楼: Originally posted by hakuna at 2012-05-25 22:56:27
多敲了个I,那个地址应该是OPENMP,还有VASP测试结果...

NERSC provides a large number of precompiled Materials Science and Chemistry application codes, while majority of them are still flat MPI codes, eg., VASP, some of them have already had OpenMP directives added in the codes, eg., Quantum Espresso. To help to address the reduced per core memory on Hopper, and to take advantage of the imporved performance from using OpenMP, we chose two representative density functional theory (DFT) codes, VASP and Quantum Espresso codes, and analyzed their performance on Hopper upon the use of OpenMP and/or the multi-threaded BLAS library.

VASP is an application for performing ab-initio quantum-mechanical molecular dynamics (MD) calculations using pseudopotentials and a plane wave basis set. Currently it is the most frequently used DFT code at NERSC. VASP is written in Fortran90 and is parallelized with MPI. The current version of VASP (5.2.11) does not have OpenMP implemented in the code. However, by linking the code to the Cray multi-threaded scientific library (-lsci_mc12_mp) we are able to get some measure of the effects of threading upon its performance. This is a low-effort OpenMP implementation. We mesured the runtime and the memory usage of the two most commonly used iteration schemes, the RMM-DIIS and the blocked Davidson, for electronic iterations with two test cases that NERSC users provided.

3楼: Originally posted by dxf_dxf_dxf at 2012-05-24 19:20:06:
如果你想用多个进程同时计算，就需要使用MPI。VASP是不支持OpenMP的。
如果你不安装MPI，一个计算任务就只有一个进程。
BTW，问一句CPU的个数和核的个数不一样啊？