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use Hyper-Threading consistently

This commit is contained in:
Axel Kohlmeyer 2018-08-22 21:54:41 -04:00
parent eca0487daf
commit 9a8c09288f
2 changed files with 8 additions and 8 deletions
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14
doc/src/Speed_kokkos.txt
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@ -93,12 +93,12 @@ The "t Nt" option specifies how many OpenMP threads per MPI task to
use with a node. The default is Nt = 1, which is MPI-only mode. Note
that the product of MPI tasks * OpenMP threads/task should not exceed
the physical number of cores (on a node), otherwise performance will
suffer. If hyperthreading is enabled, then the product of MPI tasks *
OpenMP threads/task should not exceed the physical number of cores *
hardware threads. The "-k on" switch also issues a "package kokkos"
command (with no additional arguments) which sets various KOKKOS
options to default values, as discussed on the "package"_package.html
command doc page.
suffer. If Hyper-Threading (HT) is enabled, then the product of MPI
tasks * OpenMP threads/task should not exceed the physical number of
cores * hardware threads. The "-k on" switch also issues a
"package kokkos" command (with no additional arguments) which sets
various KOKKOS options to default values, as discussed on the
"package"_package.html command doc page.
The "-sf kk" "command-line switch"_Run_options.html will automatically
append the "/kk" suffix to styles that support it. In this manner no
@ -149,7 +149,7 @@ Intel Knight's Landing (KNL) Xeon Phi:
KNL Intel Phi chips have 68 physical cores. Typically 1 to 4 cores are
reserved for the OS, and only 64 or 66 cores are used. Each core has 4
hyperthreads,so there are effectively N = 256 (4*64) or N = 264 (4*66)
Hyper-Threads,so there are effectively N = 256 (4*64) or N = 264 (4*66)
cores to run on. The product of MPI tasks * OpenMP threads/task should
not exceed this limit, otherwise performance will suffer. Note that
with the KOKKOS package you do not need to specify how many KNLs there

2
doc/src/package.txt
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@ -363,7 +363,7 @@ specified with the OMP_NUM_THREADS environment variable or the {omp}
keyword). The extra thread is dedicated for performing part of the
"PPPM solver"_kspace_style.html computations and communications. This
can improve parallel performance on processors supporting
Simultaneous Multithreading (SMT) such as Hyperthreading on Intel
Simultaneous Multithreading (SMT) such as Hyper-Threading (HT) on Intel
processors. In this mode, one additional thread is generated per MPI
process. LAMMPS will generate a warning in the case that more threads
are used than available in SMT hardware on a node. If the PPPM solver