Difference between revisions of "Machine issues & portability"

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On this page we provide links to compiler-specific information.
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#REDIRECT [[GEOS-Chem_basics#Fortran resources]]
 
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== GNU Fortran compiler ==
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'''The GNU Fortran compiler is our recommended open-source compiler for GEOS-Chem.''' Because gfortran is open-source, it can be used on a wide variety of platforms, including the [[http://cloud.geos-chem.org Amazon Web Services cloud computing platform]].  GEOS-Chem is now compatible with gfortran 4.4.7 and higher. As of December 2018, the current version is gfortran 8.2.0.
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Please see [[GNU Fortran compiler|our ''GNU Fortran compiler'' wiki page]] for more information about the compilation options used by GEOS-Chem, as well as [[GNU_Fortran_compiler#Known_issues|a list of known issues]].
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We are currently experimenting with the use of Linux containers (such as Singularity) in order to provide a consistent computational environment (i.e. with the same libraries and compiler verisons) that can be used across multiple platforms.  For more information, please see: [https://cloud-gc.readthedocs.io/en/latest/chapter03_advanced-tutorial/container.html this tutorial by Jiawei Zhuang].
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'''A note on performance:''' When GEOS-Chem is compiled with the GNU Fortran compiler, it runs slower than when compiled with the proprietary Intel Fortran compiler, especially when running on Intel CPUs.  This is because GNU Fortran, as an open-source software product, lacks the ability to take advantage of some proprietary Intel CPU optimizations.  If performance matters to you, and your institution has an Intel site license, then you might want to consider using [[Intel Fortran Compiler|the Intel Fortran Compiler]] instead. 
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--[[User:Bmy|Bob Yantosca]] ([[User talk:Bmy|talk]]) 19:34, 10 January 2019 (UTC)
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== Intel Fortran Compiler ==
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'''The Intel Fortran compiler is our recommended proprietary compiler for GEOS-Chem.'''  Although Intel Fortran requires the purchase of an expensive site license, you will always obtain the best GEOS-Chem performance when compiling with Intel Fortran and running on a system that has Intel CPUs.
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Please see [[Intel Fortran Compiler|our ''Intel Fortran Compiler'' wiki page]] for more information about the options used to compile GEOS-Chem, as well as [[Intel Fortran Compiler#Known issues|a list of known issues]].
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'''NOTE:''' If your computer system does not have the Intel Fortran Compiler available, or if you are running on a cloud-computing platform such as Amazon Web Services EC2, then you should use the free and open-source GNU Fortran compiler instead.
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--[[User:Bmy|Bob Yantosca]] ([[User talk:Bmy|talk]]) 19:37, 10 January 2019 (UTC)
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Latest revision as of 21:54, 10 January 2019