From 9a8c09288f04e00732dab2ba926ffd76bca1a15c Mon Sep 17 00:00:00 2001 From: Axel Kohlmeyer Date: Wed, 22 Aug 2018 21:54:41 -0400 Subject: [PATCH] use Hyper-Threading consistently --- doc/src/Speed_kokkos.txt | 14 +++++++------- doc/src/package.txt | 2 +- 2 files changed, 8 insertions(+), 8 deletions(-) diff --git a/doc/src/Speed_kokkos.txt b/doc/src/Speed_kokkos.txt index eb787df5d6..c734d642ce 100644 --- a/doc/src/Speed_kokkos.txt +++ b/doc/src/Speed_kokkos.txt @@ -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 diff --git a/doc/src/package.txt b/doc/src/package.txt index 8b0581929f..65117ba3c3 100644 --- a/doc/src/package.txt +++ b/doc/src/package.txt @@ -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