forked from lijiext/lammps
88 lines
2.7 KiB
HTML
88 lines
2.7 KiB
HTML
<HTML>
|
|
<CENTER><A HREF = "Section_packages.html">Previous Section</A> - <A HREF = "http://lammps.sandia.gov">LAMMPS WWW Site</A> -
|
|
<A HREF = "Manual.html">LAMMPS Documentation</A> - <A HREF = "Section_commands.html#comm">LAMMPS Commands</A>
|
|
</CENTER>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<HR>
|
|
|
|
<P><A HREF = "Section_accelerate.html">Return to Section accelerate overview</A>
|
|
</P>
|
|
<H4>5.3.6 OPT package
|
|
</H4>
|
|
<P>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.
|
|
</P>
|
|
<P>Here is a quick overview of how to use the OPT package:
|
|
</P>
|
|
<UL><LI>include the OPT package and build LAMMPS
|
|
<LI>use OPT pair styles in your input script
|
|
</UL>
|
|
<P>The last step can be done using the "-sf opt" <A HREF = "Section_start.html#start_7">command-line
|
|
switch</A>. Or the effect of the "-sf" switch
|
|
can be duplicated by adding a <A HREF = "suffix.html">suffix opt</A> command to your
|
|
input script.
|
|
</P>
|
|
<P><B>Required hardware/software:</B>
|
|
</P>
|
|
<P>None.
|
|
</P>
|
|
<P><B>Building LAMMPS with the OPT package:</B>
|
|
</P>
|
|
<P>Include the package and build LAMMPS:
|
|
</P>
|
|
<P>To do this in one line, use the src/Make.py script, described in
|
|
<A HREF = "Section_start.html#start_4">Section 2.4</A> of the manual. Type "Make.py
|
|
-h" for help. If run from the src directory, this command will create
|
|
src/lmp_opt using src/MAKE/Makefile.mpi as the starting
|
|
Makefile.machine:
|
|
</P>
|
|
<PRE>Make.py -p opt -o opt file mpi
|
|
</PRE>
|
|
<P>Or you can follow these steps:
|
|
</P>
|
|
<PRE>cd lammps/src
|
|
make yes-opt
|
|
make machine
|
|
</PRE>
|
|
<P>If you are using Intel compilers, then the CCFLAGS setting in
|
|
Makefile.machine needs to include "-restrict".
|
|
</P>
|
|
<P><B>Run with the OPT package from the command line:</B>
|
|
</P>
|
|
<P>Use the "-sf opt" <A HREF = "Section_start.html#start_7">command-line switch</A>,
|
|
which will automatically append "opt" to styles that support it.
|
|
</P>
|
|
<PRE>lmp_machine -sf opt -in in.script
|
|
mpirun -np 4 lmp_machine -sf opt -in in.script
|
|
</PRE>
|
|
<P><B>Or run with the OPT package by editing an input script:</B>
|
|
</P>
|
|
<P>Use the <A HREF = "suffix.html">suffix opt</A> command, or you can explicitly add an
|
|
"opt" suffix to individual styles in your input script, e.g.
|
|
</P>
|
|
<PRE>pair_style lj/cut/opt 2.5
|
|
</PRE>
|
|
<P><B>Speed-ups to expect:</B>
|
|
</P>
|
|
<P>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.
|
|
</P>
|
|
<P><B>Guidelines for best performance:</B>
|
|
</P>
|
|
<P>None. Just try out an OPT pair style to see how it performs.
|
|
</P>
|
|
<P><B>Restrictions:</B>
|
|
</P>
|
|
<P>None.
|
|
</P>
|
|
</HTML>
|