2011-06-01 07:08:32 +08:00
|
|
|
<HTML>
|
|
|
|
|
<CENTER><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>
|
|
|
|
|
|
|
|
|
|
<H3>package command
|
|
|
|
|
</H3>
|
|
|
|
|
<P><B>Syntax:</B>
|
|
|
|
|
</P>
|
|
|
|
|
<PRE>package style args
|
|
|
|
|
</PRE>
|
2011-08-17 22:20:30 +08:00
|
|
|
<UL><LI>style = <I>gpu</I> or <I>cuda</I> or <I>omp</I>
|
2011-06-01 07:08:32 +08:00
|
|
|
|
2011-08-17 22:20:30 +08:00
|
|
|
<LI>args = arguments specific to the style
|
2011-06-01 07:08:32 +08:00
|
|
|
|
2011-08-17 22:22:48 +08:00
|
|
|
<PRE> <I>gpu</I> args = mode first last split
|
|
|
|
|
mode = force or force/neigh
|
|
|
|
|
first = ID of first GPU to be used on each node
|
|
|
|
|
last = ID of last GPU to be used on each node
|
|
|
|
|
split = fraction of particles assigned to the GPU
|
|
|
|
|
<I>cuda</I> args = to be determined
|
|
|
|
|
<I>omp</I> args = Nthreads
|
|
|
|
|
Nthreads = # of OpenMP threads to associate with each MPI process
|
2011-06-01 07:08:32 +08:00
|
|
|
</PRE>
|
|
|
|
|
|
|
|
|
|
</UL>
|
|
|
|
|
<P><B>Examples:</B>
|
|
|
|
|
</P>
|
2011-08-17 22:20:30 +08:00
|
|
|
<PRE>package gpu force 0 0 1.0
|
|
|
|
|
package gpu force 0 0 0.75
|
|
|
|
|
package gpu force/neigh 0 0 1.0
|
|
|
|
|
package gpu force/neigh 0 1 -1.0
|
|
|
|
|
package cuda blah
|
|
|
|
|
package omp 4
|
2011-06-01 07:08:32 +08:00
|
|
|
</PRE>
|
|
|
|
|
<P><B>Description:</B>
|
|
|
|
|
</P>
|
2011-08-17 22:20:30 +08:00
|
|
|
<P>This command invokes package-specific settings. Currently the
|
|
|
|
|
following packages use it: GPU, USER-CUDA, and USER-OMP.
|
|
|
|
|
</P>
|
2011-08-17 22:22:48 +08:00
|
|
|
<P>See <A HREF = "Section_accelerate.html">this section</A> of the manual for more
|
2011-08-17 22:20:30 +08:00
|
|
|
details about using these various packages for accelerating
|
|
|
|
|
a LAMMPS calculation.
|
|
|
|
|
</P>
|
|
|
|
|
<HR>
|
|
|
|
|
|
|
|
|
|
<P>The <I>gpu</I> style invokes options associated with the use of the GPU
|
|
|
|
|
package. It allows you to select and initialize GPUs to be used for
|
|
|
|
|
acceleration via this package and configure how the GPU acceleration
|
|
|
|
|
is performed. These settings are required in order to use any style
|
|
|
|
|
with GPU acceleration.
|
|
|
|
|
</P>
|
|
|
|
|
<P>The <I>mode</I> setting specifies where neighbor list calculations will be
|
|
|
|
|
performed. If <I>mode</I> is force, neighbor list calculation is performed
|
|
|
|
|
on the CPU. If <I>mode</I> is force/neigh, neighbor list calculation is
|
|
|
|
|
performed on the GPU. GPU neighbor list calculation currently cannot
|
|
|
|
|
be used with a triclinic box. GPU neighbor list calculation currently
|
|
|
|
|
cannot be used with <A HREF = "pair_hybrid.html">hybrid</A> pair styles. GPU
|
|
|
|
|
neighbor lists are not compatible with styles that are not
|
|
|
|
|
GPU-enabled. When a non-GPU enabled style requires a neighbor list,
|
|
|
|
|
it will also be built using CPU routines. In these cases, it will
|
|
|
|
|
typically be more efficient to only use CPU neighbor list builds.
|
|
|
|
|
</P>
|
|
|
|
|
<P>The <I>first</I> and <I>last</I> settings specify the GPUs that will be used for
|
|
|
|
|
simulation. On each node, the GPU IDs in the inclusive range from
|
|
|
|
|
<I>first</I> to <I>last</I> will be used.
|
|
|
|
|
</P>
|
|
|
|
|
<P>The <I>split</I> setting can be used for load balancing force calculation
|
|
|
|
|
work between CPU and GPU cores in GPU-enabled pair styles. If 0 <
|
|
|
|
|
<I>split</I> < 1.0, a fixed fraction of particles is offloaded to the GPU
|
|
|
|
|
while force calculation for the other particles occurs simulataneously
|
|
|
|
|
on the CPU. If <I>split</I><0, the optimal fraction (based on CPU and GPU
|
|
|
|
|
timings) is calculated every 25 timesteps. If <I>split</I> = 1.0, all force
|
|
|
|
|
calculations for GPU accelerated pair styles are performed on the
|
|
|
|
|
GPU. In this case, <A HREF = "pair_hybrid.html">hybrid</A>, <A HREF = "bond_style.html">bond</A>,
|
|
|
|
|
<A HREF = "angle_style.html">angle</A>, <A HREF = "dihedral_style.html">dihedral</A>,
|
|
|
|
|
<A HREF = "improper_style.html">improper</A>, and <A HREF = "kspace_style.html">long-range</A>
|
|
|
|
|
calculations can be performed on the CPU while the GPU is performing
|
|
|
|
|
force calculations for the GPU-enabled pair style. If all CPU force
|
|
|
|
|
computations complete before the GPU, LAMMPS will block until the GPU
|
|
|
|
|
has finished before continuing the timestep.
|
|
|
|
|
</P>
|
|
|
|
|
<P>As an example, if you have two GPUs per node and 8 CPU cores per node,
|
|
|
|
|
and would like to run on 4 nodes (32 cores) with dynamic balancing of
|
|
|
|
|
force calculation across CPU and GPU cores, you could specify
|
2011-06-01 07:08:32 +08:00
|
|
|
</P>
|
2011-08-17 22:20:30 +08:00
|
|
|
<PRE>package gpu force/neigh 0 1 -1
|
|
|
|
|
</PRE>
|
|
|
|
|
<P>In this case, all CPU cores and GPU devices on the nodes would be
|
|
|
|
|
utilized. Each GPU device would be shared by 4 CPU cores. The CPU
|
|
|
|
|
cores would perform force calculations for some fraction of the
|
|
|
|
|
particles at the same time the GPUs performed force calculation for
|
|
|
|
|
the other particles.
|
|
|
|
|
</P>
|
|
|
|
|
<HR>
|
|
|
|
|
|
2011-06-01 07:08:32 +08:00
|
|
|
<P>The <I>cuda</I> style invokes options associated with the use of the
|
2011-08-18 05:55:22 +08:00
|
|
|
USER-CUDA package. These still need to be documented.
|
2011-08-17 22:20:30 +08:00
|
|
|
</P>
|
|
|
|
|
<HR>
|
|
|
|
|
|
|
|
|
|
<P>The <I>omp</I> style invokes options associated with the use of the
|
|
|
|
|
USER-OMP package.
|
2011-06-01 07:08:32 +08:00
|
|
|
</P>
|
2011-08-17 22:20:30 +08:00
|
|
|
<P>The only setting to make is the number of OpenMP threads to be
|
|
|
|
|
allocated for each MPI process. For example, if your system has nodes
|
|
|
|
|
with dual quad-core processors, it has a total of 8 cores per node.
|
|
|
|
|
You could run MPI on 2 cores on each node (e.g. using options for the
|
|
|
|
|
mpirun command), and set the <I>Nthreads</I> setting to 4. This would
|
|
|
|
|
effectively use all 8 cores on each node. Since each MPI process
|
|
|
|
|
would spawn 4 threads (one of which runs as part of the MPI process
|
|
|
|
|
itself).
|
|
|
|
|
</P>
|
|
|
|
|
<P>For performance reasons, you should not set <I>Nthreads</I> to more threads
|
|
|
|
|
than there are physical cores, but LAMMPS does not check for this.
|
|
|
|
|
</P>
|
|
|
|
|
<HR>
|
|
|
|
|
|
2011-06-01 07:08:32 +08:00
|
|
|
<P><B>Restrictions:</B>
|
|
|
|
|
</P>
|
2011-08-17 22:20:30 +08:00
|
|
|
<P>This command cannot be used after the simulation box is defined by a
|
|
|
|
|
<A HREF = "read_data.html">read_data</A> or <A HREF = "create_box.html">create_box</A> command.
|
|
|
|
|
</P>
|
2011-06-01 07:08:32 +08:00
|
|
|
<P>The cuda style of this command can only be invoked if LAMMPS was built
|
2011-08-26 00:46:23 +08:00
|
|
|
with the USER-CUDA package. See the <A HREF = "Section_start.html#start_3">Making
|
2011-06-01 07:08:32 +08:00
|
|
|
LAMMPS</A> section for more info.
|
|
|
|
|
</P>
|
2011-08-17 22:20:30 +08:00
|
|
|
<P>The gpu style of this command can only be invoked if LAMMPS was built
|
2011-08-26 00:46:23 +08:00
|
|
|
with the GPU package. See the <A HREF = "Section_start.html#start_3">Making
|
|
|
|
|
LAMMPS</A> section for more info.
|
2011-06-01 07:08:32 +08:00
|
|
|
</P>
|
2011-08-17 22:20:30 +08:00
|
|
|
<P>The omp style of this command can only be invoked if LAMMPS was built
|
2011-08-26 00:46:23 +08:00
|
|
|
with the USER-OMP package. See the <A HREF = "Section_start.html#start_3">Making
|
2011-08-17 22:20:30 +08:00
|
|
|
LAMMPS</A> section for more info.
|
2011-06-01 07:08:32 +08:00
|
|
|
</P>
|
2011-08-17 22:20:30 +08:00
|
|
|
<P><B>Related commands:</B> none
|
2011-06-01 07:08:32 +08:00
|
|
|
</P>
|
|
|
|
|
<P><B>Default:</B> none
|
|
|
|
|
</P>
|
|
|
|
|
</HTML>
|
