Environment Variables

SeisSol can be tuned with several environment variables:

Output

The wave field and fault output use the XdmfWriter. Tuning variables for the XdmfWriter are listed in the corresponding wiki.

Asynchronous Output

In addition to the variables in SeisSol, the ASYNC library provides some tuning variables listed in the wiki.

Checkpointing

Some environment variables related to checkpointing are described in the Checkpointing section.

Optimal environment variables on SuperMUC-NG

On SuperMUC-NG, we recommend using SeisSol with async output in thread mode. That is SeisSol should be compiled with -DCOMMTHREAD=ON, and then run with the environment variables proposed below. Also, we recommend using hyperthreading capabilities (that is using 96 CPUs instead of 48. 2 threads out of 96 are used as communication threads). Here are some proposed environment variables, to be added prior to invoking SeisSol in your batch file:

export MP_SINGLE_THREAD=no
unset KMP_AFFINITY
export OMP_NUM_THREADS=94
export OMP_PLACES="cores(47)"

export XDMFWRITER_ALIGNMENT=8388608
export XDMFWRITER_BLOCK_SIZE=8388608
export SC_CHECKPOINT_ALIGNMENT=8388608
export SEISSOL_CHECKPOINT_ALIGNMENT=8388608
export SEISSOL_CHECKPOINT_DIRECT=1

export ASYNC_MODE=THREAD
export ASYNC_BUFFER_ALIGNMENT=8388608

A complete batch script for SuperMUC-NG can be found in the chapter about SuperMUC-NG.