hi
I read that LAMMPS has another very nice feature: it can run replicates under one mpirun. My problem is I can’t quite understand the man pages, quoting here:
Invoke LAMMPS in multi-partition mode. When LAMMPS is run on P processors and this switch is not used, LAMMPS runs in one partition, i.e. all P processors run a single simulation. If this switch is used, the P processors are split into separate partitions and each partition runs its own simulation. The arguments to the switch specify the number of processors in each partition. Arguments of the form MxN mean M partitions, each with N processors. Arguments of the form N mean a single partition with N processors. The sum of processors in all partitions must equal P. Thus the command “-partition 8x2 4 5” has 10 partitions and runs on a total of 25 processors.
this
MxN mean M partitions, each with N processors
make perfect sense but this:
Thus the command “-partition 8x2 4 5” has 10 partitions and runs on a total of 25 processors.
doesn’t for me. It seems that “-partition 8x2” would run 8 independent partitions with 2 cores each in a MPI world of 16 processors.
What are the “4 5” for (and how does the command result in “10 partitions and runs on a total of 25 processors”)?
I am sure it is obvious, but unfortunately not to me,
Reese
ps It is also my understanding that a “universe” variable creates a stack from which each of the partitions will eat away at until the stack is gone.