LASYNC: Difference between revisions

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Description: Controls the overlap in communication.  
Description: Controls the overlap in communication.  
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If {{TAG|LASYNC}}=''.TRUE.'' is set in the INCAR file, VASP will try to overlap communication with calculations. This switch is only supported in VASP.4.5 and newer releases, its use is however not recommended, since  {{TAG|LASYNC}}=''.TRUE.'' has not been tested carefully.
If {{TAG|LASYNC}}=''.TRUE.'' is set in the INCAR file, VASP will try to overlap communication with calculations.
 
This might improve performance or degrade it depending on the MPI library and hardware you are running on.
Overlapping communication and calculations, might improve performance a little bit, but it is also possible that the performance drops significantly. Please try yourself.
Please do your own testing and compare the runtimes and results before using this tag in production runs.
Compiling VASP using the [[Precompiler_options#-DPROFILING|-DPROFILING]] precompiler switch provides a detailed timing of the different VASP routines which helps in determining if there is a performance gain.
Please report any issues in the [https://www.vasp.at/forum/ VASP forum].


{{sc|LASYNC|Examples|Examples that use this tag}}
{{sc|LASYNC|Examples|Examples that use this tag}}

Latest revision as of 08:12, 19 July 2022

LASYNC = [logical]
Default: LASYNC = .FALSE. 

Description: Controls the overlap in communication.


If LASYNC=.TRUE. is set in the INCAR file, VASP will try to overlap communication with calculations. This might improve performance or degrade it depending on the MPI library and hardware you are running on. Please do your own testing and compare the runtimes and results before using this tag in production runs. Compiling VASP using the -DPROFILING precompiler switch provides a detailed timing of the different VASP routines which helps in determining if there is a performance gain. Please report any issues in the VASP forum.

Examples that use this tag