MAXMEM: Difference between revisions
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with 12 Gbyte, and 6 MPI ranks share this memory, the recommended setting is 12*1024/6-200 = 1848. | with 12 Gbyte, and 6 MPI ranks share this memory, the recommended setting is 12*1024/6-200 = 1848. | ||
As of VASP.6 the default value of MAXMEM is set to 90 percent of the available memory per MPI rank of the node | As of VASP.6 the default value of MAXMEM is set to 90 percent of the available memory per MPI rank of the node and if more than one computation node is used, the minimum of all nodes is used. By this purpose VASP tries to open the file "/proc/meminfo" and looks for the entry "MemFree:". This file is present on any Linux system and stored in RAM. | ||
If the file cannot be found MAXMEM is set to 2800. | |||
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Revision as of 13:02, 12 August 2019
MAXMEM = [integer]
Default: MAXMEM = 2800 (VASP.5.4.4. and older), automatically set as of VASP.6
Description: MAXMEM specifies the maximum memory one MPI rank will attempt to allocate (in MByte). Since, the default varies somewhat between VASP versions, it is safer to set this flag manually. Currently the flag is only inspected in few selected routines, such as the GW or RPA routines that can use excessive amounts of memory. It is recommended to set MAXMEM to the available memory per core minus 200 Mbyte. For instance, if one node is equipped with 12 Gbyte, and 6 MPI ranks share this memory, the recommended setting is 12*1024/6-200 = 1848.
As of VASP.6 the default value of MAXMEM is set to 90 percent of the available memory per MPI rank of the node and if more than one computation node is used, the minimum of all nodes is used. By this purpose VASP tries to open the file "/proc/meminfo" and looks for the entry "MemFree:". This file is present on any Linux system and stored in RAM. If the file cannot be found MAXMEM is set to 2800.