"make" is another rather complex unix utilities that compiles what is needed in the way it is needed and in the order in which is needed (in Fortran-90 you need to compile modules before programs that use them, for instance). The configuration files for "make" are either coming with the package or automatically generated by "configure". If everything goes well, there will be a bunch of executables in "bin/":
ls bin/*.x
10. Quick test (for "pw.x" executable oly) to verify that things look good:
11. cd tests
12. ./check-pw.x.j
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REQUIREMENTS FOR INSTALLATION OF A FAST EXECUTABLE
Most of the CPU time in a typical run is spent in:
• Fast Fourier Transform
• matrix-matrix and matrix-vector multiplications (BLAS)
• solution of linear systems, diagonalizations (LAPACK)
If you want a fast executable, you MUST provide:
• machine-optimized BLAS (VERY important) and LAPACK libraries (important)
• for some architectures (in particular IBM SP): machine-optimized FFT library
Most vendors provide highly optimized BLAS and LAPACK replacements and FFT libraries (different from FFTW)
MACHINE-OPTIMIZED LIBRARIES: BLAS, LAPACK
The "configure" scripts can recognize and use the following architecture-specific replacements for BLAS and LAPACK:
• essl for IBM RISC and SP machines
• MKL for Intel/AMD PCs
• ACML for AMD (e.g. Opterons) PCs
• complib.sgimath for SGI Origin
• SCSL for SGI Altix
• sunperf for Sun workstations and parallel machines
• cxml for HP-Compaq workstations and parallel machines with Alpha CPU and Unix (not Linux)
If none of these is available, you should try the ATLAS (Automatically Tuned Linear Algebra Subroutines) library: https://math-atlas.sourceforge.net
MACHINE-OPTIMIZED LIBRARIES: FFT
Quantum-ESPRESSO can use the following architecture-specific mathematical libraries instead of FFTW:
• essl for IBM RISC and SP machines
• complib.sgimath for SGI Origin
• SCSL for SGI Altix
• sunperf for Sun workstations and parallel machines
and for a few more exotic architectures. Support for FFT's contained in Intel MKL v.8 and later requires to compile and link the appropriate interface provided by Intel. If none of the above is available, a precompiled FFTW library (v.2; support for v.3 is present but still experimental) or the built-in FFTW library contained in the distribution will be fine. Their performances are quite decent. Only ESSL on IBM machines beats them by a large margin.
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