For the GPU package, using this command-line switch also invokes the +default GPU settings, as if the command "package gpu force/neigh 0 0 +1" were used at the top of your input script. These settings can be +changed by using the package gpu command in your script +if desired. +
+For the OMP package, using this command-line switch also invokes the +default OMP settings, as if the command "package omp *" were used at +the top of your input script. These settings can be changed by using +the package omp command in your script if desired.
The suffix command can also set a suffix and it can also turn off/on any suffix setting made via the command line. diff --git a/doc/Section_start.txt b/doc/Section_start.txt index 12492f09f3..f2cb42e1b4 100644 --- a/doc/Section_start.txt +++ b/doc/Section_start.txt @@ -990,12 +990,22 @@ lj/cut"_pair_lj.html variant, with style names lj/cut/opt, lj/cut/omp, lj/cut/gpu, or lj/cut/cuda. A variant styles can be specified explicitly in your input script, e.g. pair_style lj/cut/gpu. If the -suffix switch is used, you do not need to modify your input script. -The specified suffix (opt,omp,gpu,cuda) is automatically appended whenever -your input script command creates a new "atom"_atom_style.html, -"pair"_pair_style.html, "fix"_fix.html, "compute"_compute.html, or -"run"_run_style.html style. atom, pair, fix, compute, or integrate -style. If the variant version does not exist, the standard version is -created. +The specified suffix (opt,omp,gpu,cuda) is automatically appended +whenever your input script command creates a new +"atom"_atom_style.html, "pair"_pair_style.html, "fix"_fix.html, +"compute"_compute.html, or "run"_run_style.html style. If the variant +version does not exist, the standard version is created. + +For the GPU package, using this command-line switch also invokes the +default GPU settings, as if the command "package gpu force/neigh 0 0 +1" were used at the top of your input script. These settings can be +changed by using the "package gpu"_pacakge.html command in your script +if desired. + +For the OMP package, using this command-line switch also invokes the +default OMP settings, as if the command "package omp *" were used at +the top of your input script. These settings can be changed by using +the "package omp"_pacakge.html command in your script if desired. The "suffix"_suffix.html command can also set a suffix and it can also turn off/on any suffix setting made via the command line. diff --git a/doc/package.html b/doc/package.html index b900dd4b7a..9b750c49af 100644 --- a/doc/package.html +++ b/doc/package.html @@ -24,7 +24,18 @@ 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 - cuda args = to be determined + cuda args = one or more keyword/value pairs may be appended + keywords = gpu/node or gpu/node/special or timing or test or override/bpa + gpu/node values = N + N = number of GPUs to be used per node + gpu/node/special values = N gpu1 .. gpuN + N = number of GPUs to be used per node + gpu1 .. gpuN = N IDs of the GPUs to use + timing values = none + test values = id + id = atom-ID of a test particle + override/bpa values = flag + flag = 0 for TpA algorithm, 1 for BpA algorithm omp args = Nthreads mode Nthreads = # of OpenMP threads to associate with each MPI process mode = force or force/neigh (optional) @@ -45,17 +56,25 @@ package omp 4 force
This command invokes package-specific settings. Currently the following packages use it: GPU, USER-CUDA, and USER-OMP.
+To use the accelerated GPU and USER-OMP styles, the use of the package +command is required. However, as described in the "Defaults" section +below, if you use the "-sf gpu" or "-sf omp" command-line +options to enable use of these styles, +then default package settings are enabled. In that case you only need +to use the package command if you want to change the defaults. +
+To use the accelerate USER-CUDA styles, the package command is not +required as defaults are assigned internally. You only need to use +the package command if you want to change the defaults. +
See this section of the manual for more -details about using these various packages for accelerating -a LAMMPS calculation. +details about using these various packages for accelerating LAMMPS +calculations.
The gpu 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. +package.
The mode setting specifies where neighbor list calculations will be performed. If mode is force, neighbor list calculation is performed @@ -102,7 +121,54 @@ the other particles.
The cuda style invokes options associated with the use of the -USER-CUDA package. These still need to be documented. +USER-CUDA package. +
+The gpu/node setting specifies the number N of GPUs to be used on +each node. An MPI process with rank K will use the GPU (K mod N). +This implies that processes should be assigned with successive ranks +on each node, which is the default with most (or even all) MPI +implementations. The default value for N is 2. +
+The gpu/node/special setting also specifies the number (N) of GPUs +to be used on each node, but allows more control over their +specification. An MPI process with rank K will use the GPU gpuI +with l = (K mod N) + 1. This implies that processes should be assigned +with successive ranks on each node, which is the default with most (or +even all) MPI implementations. For example if you have three GPUs on +a machine, one of which is used for the X-Server (the GPU with the ID +1) while the others (with IDs 0 and 2) are used for computations you +would specify: +
+package cuda gpu/node/special 2 0 2 ++
A main purpose of the gpu/node/special option is to allow two (or +more) simulations to be run on one workstation. In that case one +would set the first simulation to use GPU 0 and the second to use GPU +1. This is not necessary though, if the GPUs are in what is called +compute exclusive mode. Using that setting, every process will get +its own GPU automatically. This compute exclusive mode can be set +as root using the nvidia-smi tool which is part of the CUDA +installation. +
+Note that if the gpu/node/special keyword is not used, the USER-CUDA +package sorts existing GPUs on each node according to their number of +multiprocessors. This way, compute GPUs will be priorized over +X-Server GPUs. +
+Use of the timing keyword will output detailed timing information +for various subroutines. +
+The test keyword will output info for the the specified atom at +several points during each time step. This is mainly usefull for +debugging purposes. Note that the simulation will be severly slowed +down if this option is used. +
+The override/bpa keyword can be used to specify which mode is used +for pair-force evaluation. TpA = one thread per atom; BpA = one block +per atom. If this keyword is not used, a short test at the begin of +each run will determine which method is more effective (the result of +this test is part of the LAMMPS output). Therefore it is usually not +necessary to use this setting.
The cuda style of this command can only be invoked if LAMMPS was built with the USER-CUDA package. See the Making -LAMMPS section for more info. When using -styles in the USER-CUDA package, use of the "package cuda" command in -your input script is not required. +LAMMPS section for more info.
The gpu style of this command can only be invoked if LAMMPS was built with the GPU package. See the Making -LAMMPS section for more info. When using -styles in the GPU package, use of the "package gpu" command in your -input script is currently required. +LAMMPS section for more info.
The omp style of this command can only be invoked if LAMMPS was built with the USER-OMP package. See the Making -LAMMPS section for more info. When using -styles in the USER-OMP package, use of the "package omp" command in -your input script is not required. See the information on default -settings below. +LAMMPS section for more info.
Related commands:
@@ -176,10 +235,20 @@ settings below.Default:
-If the "-sf omp" command-line switch is -used then "package omp *" is also auto-invoked to specify default OMP -settings. +
If the "-sf gpu" command-line switch is +used then it is as if the command "package gpu force/neigh 0 0 1" were +invoked, to specify default settings for the GPU package. If the +command-line switch is not used, then no defaults are set, and you +must specify the appropriate package command in your input script.
-The other styles have no defaults. +
The default settings for the USER CUDA package are "package cuda gpu +2". This is the case whether the "-sf cuda" command-line +switch is used or not. +
+If the "-sf omp" command-line switch is +used then it is as if the command "package omp *" were invoked, to +specify default settings for the USER-OMP package. If the +command-line switch is not used, then no defaults are set, and you +must specify the appropriate package command in your input script.