forked from lijiext/lammps
75 lines
2.1 KiB
Plaintext
75 lines
2.1 KiB
Plaintext
:doc:`Return to Section accelerate overview <Section_accelerate>`
|
|
|
|
5.OPT package
|
|
-------------
|
|
|
|
The OPT package was developed by James Fischer (High Performance
|
|
Technologies), David Richie, and Vincent Natoli (Stone Ridge
|
|
Technologies). It contains a handful of pair styles whose compute()
|
|
methods were rewritten in C++ templated form to reduce the overhead
|
|
due to if tests and other conditional code.
|
|
|
|
Here is a quick overview of how to use the OPT package. More details
|
|
follow.
|
|
|
|
.. parsed-literal::
|
|
|
|
make yes-opt
|
|
make mpi # build with the OPT package
|
|
Make.py -v -p opt -o mpi -a file mpi # or one-line build via Make.py
|
|
|
|
.. parsed-literal::
|
|
|
|
lmp_mpi -sf opt -in in.script # run in serial
|
|
mpirun -np 4 lmp_mpi -sf opt -in in.script # run in parallel
|
|
|
|
**Required hardware/software:**
|
|
|
|
None.
|
|
|
|
**Building LAMMPS with the OPT package:**
|
|
|
|
The lines above illustrate how to build LAMMPS with the OPT package in
|
|
two steps, using the "make" command. Or how to do it with one command
|
|
via the src/Make.py script, described in :ref:`Section 2.4 <start_4>` of the manual. Type "Make.py -h" for
|
|
help.
|
|
|
|
Note that if you use an Intel compiler to build with the OPT package,
|
|
the CCFLAGS setting in your Makefile.machine must include "-restrict".
|
|
The Make.py command will add this automatically.
|
|
|
|
**Run with the OPT package from the command line:**
|
|
|
|
As in the lines above, use the "-sf opt" :ref:`command-line switch <start_7>`, which will automatically append
|
|
"opt" to styles that support it.
|
|
|
|
**Or run with the OPT package by editing an input script:**
|
|
|
|
Use the :doc:`suffix opt <suffix>` command, or you can explicitly add an
|
|
"opt" suffix to individual styles in your input script, e.g.
|
|
|
|
.. parsed-literal::
|
|
|
|
pair_style lj/cut/opt 2.5
|
|
|
|
**Speed-ups to expect:**
|
|
|
|
You should see a reduction in the "Pair time" value printed at the end
|
|
of a run. On most machines for reasonable problem sizes, it will be a
|
|
5 to 20% savings.
|
|
|
|
**Guidelines for best performance:**
|
|
|
|
Just try out an OPT pair style to see how it performs.
|
|
|
|
Restrictions
|
|
""""""""""""
|
|
|
|
|
|
None.
|
|
|
|
|
|
.. _lws: http://lammps.sandia.gov
|
|
.. _ld: Manual.html
|
|
.. _lc: Section_commands.html#comm
|