When VASP 5 was released, the performance was mostly slower than our make of VASP 4.6. I wrote it off as an optimization issue, and went on in my life. Then, in VASP 5.2, with the release notes, I realized that the it was all due to slower FFT, and is now fixed. Is there any way for me, as a user, to tell if the VASP make that I am using is built with the faster FFTW?
There are a few possibilities:
- Ask whoever built it. :)
- Run strings vasp | grep -i fft and see if there's evidence of the version buried in the executable.
- Run ldd vasp and look for a dynamically linked fft library. This last option is unlikely to produce results because you're more likely to have a static FFTW library (if I recall the build process for FFTW correctly).