Run It

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Operation System[edit]

lmt is available for Linux operation systems only.

How to start[edit]

lmt is always started from the Linux command line interface. In default mode, lmt will search in the run time directory for a parameter file named para.xml . Alternatively the parameter file name can be provided via the command line option -f myfilename .

Run time environment[edit]

lmt is developed for Linux operation systems on computers with an Intel architecture. Thus using lmt on AMD architecture will result in increased run time. For executables running on Windows or Mac please contact the author.

lmt requires that some environment variables are set to specific values. lmt will check those settings at start and will stop if the settings are wrong.

  • stack size must be set to unlimited via ulimit -s unlimited
  • OMP_DYNAMIC=FALSE
  • OMP_STACKSIZE='a reasonable value (i.e. 2000M)'
  • OMP_PROC_BIND=true
  • OMP_PLACES=cores
  • OMP_MAX_ACTIVE_LEVELS=2147483647
  • KMP_AFFINITY=granularity=core,scatter

lmt is highly threaded and will try to use all available computing resources. Will this is desirable for very large models it can hamper performance when crunching medium to small data sets resulting in an increased run time. What "medium to small" means depends on the actual computer and must therefore be determined by the user. The user can set the lmt threading behaviour via the two environment variables OMP_NUM_THREADS and MKL_NUM_THREADS.

Alternatively, lmt can be obtained as a dedicated single core version using single-core third party libraries, or as a dedicated single-core version using threaded third party libraries.

The performance of multi-threaded programs can also be heavily affected by thread affinity settings where the optimal settings must be found via trial and error. However, as a starting point, it is advisable to set the environment variable KMP_AFFINITY=granularity=core,scatter.

If you run several instances of lmt at the same time on the same computer you may experience a severe drop in performance of each of the runs. This is usually caused by competition for resources and therefore parallel runs of several lmt instances should be avoided. However, using the numactl environment to encapsulate lmt instances may provide an option to avoid performance drops.