Development/FFTW: Difference between revisions
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{{Softwarepage|numlib/mkl}} |
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| module load |
| module load |
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| numlib/mkl |
| numlib/mkl |
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| Availability |
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| [[bwUniCluster_2.0]] | [[BwForCluster_JUSTUS_2]] |
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| License |
| License |
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| No |
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<br> |
<br> |
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= Description = |
= Description = |
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The '''Intel Math Kernel Library (Intel MKL)''' offers FFTW2 (for version 2.x) and FFTW3 (for version 3.x) interfaces to the Intel MKL Fast Fourier Transform and Trigonometric Transform functionality. These interfaces enable applications using FFTW to gain performance with Intel MKL without changing the application source code. Therefore, it is highly recommended to use Intel MKL instead of a separate FFTW installation. |
The '''Intel Math Kernel Library (Intel MKL)''' offers FFTW2 (for version 2.x) and FFTW3 (for version 3.x) interfaces to the Intel MKL Fast Fourier Transform and Trigonometric Transform functionality. These interfaces enable applications using FFTW to gain performance with Intel MKL without changing the application source code. Therefore, it is highly recommended to use Intel MKL instead of a separate FFTW installation. |
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= Availability = |
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Intel MKL is available on selected bwHPC-Clusters. A complete list of versions currently installed on the bwHPC-Clusters can be obtained from the [https://www.bwhpc.de/software.html Cluster Information System (CIS)]. |
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In order to check which versions of Intel MKL are installed on the compute cluster, run the following command: |
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<pre> |
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$ module avail numlib/mkl |
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</pre> |
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= Documentation = |
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A documentation for Intel MKL is available [https://software.intel.com/content/www/us/en/develop/articles/intel-math-kernel-library-documentation.html online]. |
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The help page of the Intel MKL module provides more version specific information: |
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<pre> |
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$ module help numlib/mkl |
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----------- Module Specific Help for 'numlib/mkl/11.1.4' ---------- |
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This module provides the Intel(R) Math Kernel Library (MKL) |
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version 11.1.4, a fast and reliable implementation |
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of BLAS/LAPACK/FFTW (see also 'http://software.intel.com/en-us/intel-mkl/'). |
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The preferable compiler for this MKL version is 'compiler/intel/14.0'. Linking |
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with other compilers like GNU, PGI and SUN is possible. The desired compiler |
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module (exception system GNU compiler) has to be loaded before using MKL. |
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Local documentation: |
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Man pages in '$MKL_MAN_DIR/man3', e.g. 'man dotc'. |
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firefox $MKL_DOC_DIR/mkl_documentation.htm |
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acroread $MKL_DOC_DIR/l_mkl_11.1.4.211.mklman.pdf |
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acroread $MKL_DOC_DIR/l_mkl_11.1.4.211.mkl_11.1.4_lnx_userguide.pdf |
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[...] |
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Static FFTW2/3 C/Fortran interfaces can be found in dir |
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${MKL_HOME}/interfaces/ |
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Examples: |
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Link to FFTW3 Fortran interface with GNU compiler and ilp64 support: |
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${MKL_HOME}/interfaces/fftw3xf/libfftw3xf_intel64_double_i8_gnu47.a |
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Link to FFTW3 Fortran interface with Intel compiler and lp64 support: |
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${MKL_HOME}/interfaces/fftw3xf/libfftw3xf_intel64_double_i4_intel150.a |
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The Intel FFTW interfaces requires the Intel MKL library (e.g. it does |
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not work with ACML library). Usually it is not a problem to use a |
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different compiler version, e.g. to use _gnu41.a with gnu 4.3 compiler. |
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See dir ${MKL_HOME}/interfaces/ for other interfaces (fftw2/3 Fortran/C). |
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Compiler option for include files: -I${MKL_INC_DIR}/fftw |
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[...] |
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</pre> |
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After loading the module, the environment variable <span style="background:#edeae2;margin:2px;padding:1px;border:1px dotted #808080">$MKL_DOC_DIR</span> points to the local documentation folder. |
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= Usage = |
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== Loading the module == |
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You can load the default version of Intel MKL with the following command: |
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<pre> |
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$ module load numlib/mkl |
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</pre> |
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The module will try to load all modules it needs to function (e.g., compiler, mpi, ...). If loading the module fails, check if you have already loaded one of those modules, but not in the version required by MKL. |
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If you wish to load another (older) version of Intel MKL, you can do so using |
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<pre> |
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$ module load numlib/mkl/<version> |
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</pre> |
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with <version> specifying the desired version. |
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== FFTW Interface to Intel MKL == |
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To include the proper header files use the compiler option |
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-I${MKL_INC_DIR}/fftw |
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If you want to link dynamically against the FFTW functions you can just use the flag |
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-mkl |
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but when using static linking you have to link against the correct library in the directory <span style="background:#edeae2;margin:2px;padding:1px;border:1px dotted #808080">$MKL_HOME/interfaces/</span>. |
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If you need any assistance, please feel free to contact 'compchem [at] bwhpc.de' or submit a trouble ticket at https://www.bwhpc.de/supportportal. |
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= Examples = |
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| ⚫ | |||
= FAQ = |
= FAQ = |
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[[File:comparison.png|right|border| |
[[File:comparison.png|right|border|300px|Copyright: KIZ (Ulm University)]] |
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Q: Why |
'''Q:''' Why is there no FFTW module on the cluster? |
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A: MKL |
'''A:''' MKL exhibits better performance than FFTS libraries (see Figure on the right). Therefore, we recommend to use MKL and do not offer a separate FFTW installation. |
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| ⚫ | |||
Q: Why does my code crash |
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A: The interfaces do not support long double precision because Intel MKL FFT functions operate only on single- and double-precision floating point data types. For the very rare case that you need extended data |
'''A:''' The interfaces do not support long double precision because Intel MKL FFT functions operate only on single- and double-precision floating point data types. For the very rare case that you need extended data types, please submit a support ticket at https://www.bwhpc.de/supportportal. |
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= Useful links = |
= Useful links = |
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* [https://de.wikipedia.org/wiki/Math_Kernel_Library Wikipedia article (german)] |
* [https://de.wikipedia.org/wiki/Math_Kernel_Library Wikipedia article (german)] |
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* [https://en.wikipedia.org/wiki/Math_Kernel_Library Wikipedia article (english)] |
* [https://en.wikipedia.org/wiki/Math_Kernel_Library Wikipedia article (english)] |
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---- |
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[[Category:Numerical_libraries]][[Category:BwUniCluster]][[Category:BwUniCluster_2.0]][[Category:BwForCluster_Chemistry]][[Category:BwForCluster_JUSTUS_2]][[Category:BwForCluster_BinAC]] |
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Latest revision as of 00:04, 15 March 2023
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The main documentation is available via |
| Description | Content |
|---|---|
| module load | numlib/mkl |
| License | Commercial. See EULA. |
| Citing | n/a |
| Links | Intel MKL Homepage | FFTW Homepage |
| Graphical Interface | No |
Description
The Fastest Fourier Transform in the West (FFTW) is a software library for computing discrete Fourier transforms in one or more dimensions, of arbitrary input size, and of both real and complex data (as well as of even/odd data, i.e. the discrete cosine/sine transforms or DCT/DST). FFTW was developed by Matteo Frigo and Steven G. Johnson at the Massachusetts Institute of Technology.
The Intel Math Kernel Library (Intel MKL) offers FFTW2 (for version 2.x) and FFTW3 (for version 3.x) interfaces to the Intel MKL Fast Fourier Transform and Trigonometric Transform functionality. These interfaces enable applications using FFTW to gain performance with Intel MKL without changing the application source code. Therefore, it is highly recommended to use Intel MKL instead of a separate FFTW installation.
FAQ
Q: Why is there no FFTW module on the cluster?
A: MKL exhibits better performance than FFTS libraries (see Figure on the right). Therefore, we recommend to use MKL and do not offer a separate FFTW installation.
Q: Why does my code complain about argument of type "long double *" is incompatible with parameter of type "double *" ?
A: The interfaces do not support long double precision because Intel MKL FFT functions operate only on single- and double-precision floating point data types. For the very rare case that you need extended data types, please submit a support ticket at https://www.bwhpc.de/supportportal.