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| ga_installation [2024/07/12 08:37] – external edit 127.0.0.1 | ga_installation [2025/01/15 16:40] (current) – no more sockets may |
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| There are different ways (GA "runtimes") to configure the GA library which significantly affect the execution and options, and they are therefore important from a users point of view. | There are different ways (GA "runtimes") to configure the GA library which significantly affect the execution and options, and they are therefore important from a users point of view. |
| The current default of the GA installation is to use ''%%--with-mpi-ts%%'', which is **very slow** and should be avoided. | The current default of the GA installation is to use ''%%--with-mpi-ts%%'', which is **very slow** and should be avoided. |
| Our current recommendations are: | Our current recommendation is to use ''%%--with-mpi-pr%%'', preferably using the latest version of openmpi with UCX. |
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| * Use ''%%--with-sockets%%'' for single workstations and servers connected by ethernet. We recommend using [[https://www.mpich.org/ | mpich]]. | |
| * Use ''%%--with-openib%%'' for nodes connected by InfiniBand, preferably on top of the latest version of [[https://github.com/openucx/ucx/wiki/OpenMPI-and-OpenSHMEM-installation-with-UCX|openmpi with UCX]]. | |
| * When a helper process on each node can be tolerated, use ''%%--with-mpi-pr%%'', also preferably using the latest version of openmpi with UCX. | |
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| Note that openmpi may not work with ''--ga-impl disk'' when multiple parallel Molpro calculations are executed simultaneously on a node. | Note that openmpi may not work with ''--ga-impl disk'' when multiple parallel Molpro calculations are executed simultaneously on a node. |
| //Failure in doing so may result crashes or incorrect computation results.// | //Failure in doing so may result crashes or incorrect computation results.// |
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| The first two GA runtimes do not need any helper processes, but has a serious disadvantage that with ''--ga-impl ga'' (the default for multi-node calculations since Molpro 2021.2 and for all calculations in earlier versions), the GA software frequently crashes or gives wrong numbers if several GAs are allocated whose total size exceeds 16 GB (2 MW). This can be avoided by using ''--ga-impl disk'' (default for single-node calculations since Molpro 2021.2), or allocating in the beginning of the job a very large GA with at least the size of the total GA space needed in the calculation (which is not known in advance). The latter can be done with the ''-G'' or ''-M'' molpro options. | Older GA runtimes do not need any helper processes, but have a serious disadvantage that with ''--ga-impl ga'' (the default for multi-node calculations since Molpro 2021.2 and for all calculations in earlier versions), the GA software frequently crashes or gives wrong numbers if several GAs are allocated whose total size exceeds 16 GB (2 MW). This can be avoided by using ''--ga-impl disk'' (default for single-node calculations since Molpro 2021.2), or allocating in the beginning of the job a very large GA with at least the size of the total GA space needed in the calculation (which is not known in advance). The latter can be done with the ''-G'' or ''-M'' molpro options. |
| See [[Running Molpro on parallel computers]] for more details. | See [[Running Molpro on parallel computers]] for more details. |
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