Hi
I was getting horrible bad performance of QE 7.0 when build with --enable-openmp option. This did not happened with previous version (6.8) ... There was an approx. 8x speed down ... I had traced the problem to the link with fftw3_omp library witch was added in the 7.0 release for the --enable-openmp option. The code freeze on fftw routines almost. The solution was to manually edit make.ins and set: DFLAGS = -D__FFTW The code was build for Windows by Cygwin64 and gfortran ... Questions: 1) Is this an general issue with 7.0 and fftw3_omp or only a Windows specific build problem ? 2) Is there anybody on this list with Windows QE build optimization experiences ? I need somebody for consultations ... 3) I was tiring to make a pure "serial" build by setting --disable-openmp --disable-parallel option. To my surprise the result run clearly on multiple cores an almost as fast as openmp enabled build. Even with set OMP_NUM_THREADS=1. Any explanation ? Michal Husak UCT Prague _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
