Difference between revisions of "User:Manoj"

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===MKL FFTs (via FFTW wrappers)===
===MKL FFTs (via FFTW wrappers)===

Revision as of 23:17, 12 December 2012


Intel Machine ( E5-2643 @ 3.30GHz)

VASP Native FFT Library

Following library and flags were used:

MKLLIBS   = -lmkl_intel_lp64 -lmkl_sequential -lmkl_core
FFTW = Internal VASP FFTs
FFLAGS =  -free -names lowercase -assume byterecl
OFLAG  = -O2 -xsse2 -unroll-aggressive -warn general

As a first check, SIMD were changed and following is the result for MgMOS (input files can be found in the VASP):

MKL FFTs (via FFTW wrappers)

Upon profiling the code, we found that the code spends most of its time in the FFT libraries, so the next step is to change FFTW libraries. Following changes were made:

FFT_OBJS = fftmpi_map.o fftmpiw.o fftw3d.o fft3dlib.o

(The change here from original VASP makefile is inclusion of fftmpiw.o, which was not included before. It was fftmpi.o that was in the VASP FFT and was being called and we changed that)

MKLLIBS   = -lmkl_intel_lp64 -lmkl_sequential -lmkl_core
INCS = -I$(MKLDIR)/include/fftw
SIMD Instruction Time(s)
sse2 158
sse4.1 156
sse4.2 155
avx 155
ssse3 156