Changes between Version 474 and Version 475 of doc/app/initialization_parameters

Timestamp:

Aug 6, 2020 11:29:27 AM (4 years ago)

Author:

Giersch

Comment:

--

doc/app/initialization_parameters

@@ -3186 +3186 @@
 Binary format of the input and output restart files.\\\\
 Allowed values are '' 'fortran_binary' '', '' 'mpi' '', and '' 'mpi_shared_memory' ''. In case of '' 'fortran_binary' '' each core reads/writes its own file. In case of '' 'mpi' '', the I/O is done using a single file. This method can also be used in serial mode (when PALM has been compiled without {{{-D__parallel}}} option). In such a case, restart I/O is carried out using POSIX calls.\\\\
-On many-core processors the I/O speed can be significantly increased by setting '''restart_data_format''' = '' 'mpi_shared_memory' ''. With this setting, I/O is performed only by a limited number of cores on each of the nodes.
+On many-core processors the I/O speed can be increased by setting '''restart_data_format''' = '' 'mpi_shared_memory' ''. With this setting, I/O is performed only by a limited number of cores on each of the nodes. With mpi every cores writes and reads its relevant data. With mpi_shared_memory, only every 4th (or any other multiple interger of the cores per node) reads and writes data and distributes this to the other cores. This is possible since the 96 processes on a node can share their memory. With this, the IO rates increase.
 
 This parameter can also be used in the runtime parameter NAMELIST.