forked from lijiext/lammps
98 lines
3.7 KiB
Plaintext
98 lines
3.7 KiB
Plaintext
"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
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:link(lws,http://lammps.sandia.gov)
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:link(ld,Manual.html)
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:link(lc,Section_commands.html#comm)
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:line
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fix gpu command :h3
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[Syntax:]
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fix ID group-ID gpu mode first last split :pre
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ID, group-ID are documented in "fix"_fix.html command :ulb,l
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gpu = style name of this fix command :l
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mode = force or force/neigh :l
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first = ID of first GPU to be used on each node :l
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last = ID of last GPU to be used on each node :l
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split = fraction of particles assigned to the GPU :l
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:ule
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[Examples:]
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fix 0 all gpu force 0 0 1.0
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fix 0 all gpu force 0 0 0.75
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fix 0 all gpu force/neigh 0 0 1.0
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fix 0 all gpu force/neigh 0 1 -1.0 :pre
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[Description:]
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Select and initialize GPUs to be used for acceleration and configure
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GPU acceleration in LAMMPS. This fix is required in order to use
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any style with GPU acceleration. The fix must be the first fix
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specified for a run or an error will be generated. The fix will not have an
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effect on any LAMMPS computations that do not use GPU acceleration, so there
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should not be any problems with specifying this fix first in input scripts.
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{mode} specifies where neighbor list calculations will be performed.
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If {mode} is force, neighbor list calculation is performed on the
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CPU. If {mode} is force/neigh, neighbor list calculation is
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performed on the GPU. GPU neighbor
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list calculation currently cannot be used with a triclinic box.
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GPU neighbor lists are not compatible with styles that are not GPU-enabled.
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When a non-GPU enabled style requires a neighbor list, it will also be
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built using CPU routines. In these cases, it will typically be more efficient
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to only use CPU neighbor list builds. For "hybrid"_pair_hybrid.html pair
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styles, GPU calculated neighbor lists might be less efficient because
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no particles will be skipped in a given neighbor list.
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{first} and {last} specify the GPUs that will be used for simulation.
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On each node, the GPU IDs in the inclusive range from {first} to {last} will
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be used.
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{split} can be used for load balancing force calculation work between
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CPU and GPU cores in GPU-enabled pair styles. If 0<{split}<1.0,
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a fixed fraction of particles is offloaded to the GPU while force calculation
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for the other particles occurs simulataneously on the CPU. If {split}<0,
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the optimal fraction (based on CPU and GPU timings) is calculated
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every 25 timesteps. If {split}=1.0, all force calculations for
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GPU accelerated pair styles are performed
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on the GPU. In this case, "hybrid"_pair_hybrid.html,
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"bond"_bond_style.html, "angle"_angle_style.html,
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"dihedral"_dihedral_style.html, "improper"_improper_style.html,
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and "long-range"_kspace_style.html calculations can be performed on the CPU
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while the GPU is performing force calculations for the GPU-enabled pair
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style.
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In order to use GPU acceleration, a GPU enabled style must be
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selected in the input script in addition to this fix. Currently,
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this is limited to a few "pair styles"_pair_style.html.
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More details about these settings and various possible hardware
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configuration are in "this section"_Section_start.html#2_8 of the
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manual.
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[Restart, fix_modify, output, run start/stop, minimize info:]
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No information about this fix is written to "binary restart
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files"_restart.html. None of the "fix_modify"_fix_modify.html options
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are relevant to this fix.
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No parameter of this fix can be used with the {start/stop} keywords of
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the "run"_run.html command.
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[Restrictions:]
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The fix must be the first fix specified for a given run. The force/neigh
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{mode} should not be used with a triclinic box or GPU-enabled pair styles
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that need "special_bonds"_special_bonds.html settings.
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Currently, group-ID must be all.
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[Related commands:] none
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[Default:] none
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