phoebus

Phifty One Ergs Blows Up a Star

Obtaining the Source Code

phoebus uses submodules extensively. To make sure you get them all, clone it as

git clone --recursive git@github.com:lanl/phoebus.git

or as

git clone git@github.com:lanl/phoebus.git
cd phoebus
git submodule update --init --recursive

Building

Prerequisites

Here are a few tips and tricks for using and building phoebus. The first step is creating a build directory, as in-source builds are forbidden. Assuming you just cloned phoebus,

cd phoebus
mkdir bin
cd bin

You also need to make sure you have appropriate dependencies in your path. On Darwin, loading the following modules (in this order) will work:

module load gcc/7.4.0 cuda/10.2 openmpi/4.0.1-gcc_7.4.0 cmake/3.17.3

(The default build for parthenon requires Python3 loaded. This is not the case for phoebus.)

If you want output, make sure hdf5 is available as well. On Darwin, this likely means a spack environment. On snow, just load the appropriate module. If you are compiling with mpi, use hdf5-parallel, otherwise hdf5-serial.

If cmake can't find your hdf5 installation, You may have luck setting -DHDF5_ROOT=/path/to/hdf5 at configure time.

Installing hdf5 through spack

If hdf5 isn't available on your target machine, here is one way to build it, using Spack.

# download spack
git clone https://github.com/spack/spack.git
# Activate the spack bash aliases. This typically needs to be done every time you want to use spack. I have it in my bashrc
. spack/share/spack/setup-env.sh
# load your modules
module load...
# Tell spack to learn about compilers and loaded modules
spack compiler find
spack external find
# Install parallel hdf5 with high-level libraries
spack install hdf5+mpi+hl
# load it
spack load hdf5

Installing from source, or just building without hdf5 will also both probably work.

Example builds

Below are some example build commands

MPI-parallel only

The following will build phoebus with the triple problem with MPI parallelism but no shared memory parallelism

cmake ..
make -j

OpenMP-parallel

The following will build phoebus with OpenMP parallelism only

cmake -DPHOEBUS_ENABLE_MPI=Off -DPHOEBUS_ENABLE_OPENMP=ON ..
make -j

Cuda

The following will build phoebus with no MPI or OpenMP parallelism.

cmake -DPHOEBUS_ENABLE_CUDA=On -DCMAKE_CXX_COMPILER=${HOME}/phoebus/external/singularity-eos/utils/kokkos/bin/nvcc_wrapper -DKokkos_ARCH_HSW=ON -DKokkos_ARCH_VOLTA70=ON -DPHOEBUS_ENABLE_MPI=OFF ..

A few notes for this one:

• Note here the -DCMAKE_CXX_COMPILER flag. This is necessary. You must set the compiler to nvcc_wrapper provided by Kokkos.
• Note the -DKokkos_ARCH_* flags. Those set the host and device microarchitectures and are required. The choice here is on an x86_64 machine with a volta GPU.

Build Options

The build options explicitly provided by phoebus are:

Option	Default	Comment
PHOEBUS_ENABLE_CUDA	OFF	Cuda
PHOEBUS_ENABLE_HDF5	ON	HDF5. Required for output and restarts.
PHOEBUS_ENABLE_MPI	ON	MPI. Required for distributed memory parallelism.
PHOEBUS_ENABLE_OPENMP	OFF	OpenMP. Required for shared memory parallelism.
MACHINE_CFG	None	Machine-specific config file, optional.

Some relevant settings from Parthenon and Kokkos you may need to play with are:

Option	Default	Comment
CMAKE_CXX_COMPILER	None	Must be set to nvcc_wrapper with cuda backend
Kokkos_ARCH_XXXX	OFF	You must set the GPU architecture when compiling for Cuda

You can see all the Parthenon build options here and all the Kokkos build options here

Cmake machine configs

If you are proficient with cmake You can optionally write a cmake file that sets the configure parameters that you like on a given machine. Both phoebus and parthenon can make use of it. You can point to the file with

-DMACHINE_CFG=path/to/machine/file

at config time or by setting the environment variable MACHINE_CFG to point at it, e.g.,

export MACHINE_CFG=path/to/machine/file

An example machine file might look like

# Machine file for x86_64-volta on Darwin
message(STATUS "Loading machine configuration for Darwin x86-volta node")
message(STATUS "Assumes: module load module load gcc/7.4.0 cuda/10.2 openmpi/4.0.3-gcc_7.4.0 anaconda/Anaconda3.2019.10 cmake && spack load hdf5")
message(STATUS "Also assumes you have a valid spack installation loaded.")

set(PHOEBUS_ENABLE_CUDA ON CACHE BOOL "Cuda backend")
set(PHOEBUS_ENABLE_MPI OFF CACHE BOOL "No MPI")
set(Kokkos_ARCH_HSW ON CACHE BOOL "Haswell target")
set(Kokkos_ARCH_VOLTA70 ON CACHE BOOL "volta target")
set(CMAKE_CXX_COMPILER /home/jonahm/phoebus/external/parthenon/external/Kokkos/bin/nvcc_wrapper CACHE STRING "nvcc wrapper")

you could then configure and compile as

cmake -DMACHINE_CFG=path/to/machine/file ..
make -j

Running

Run phoebus from the build directory as

./src/phoebus -i path/to/input/file.phin

The input files are in phoebus/inputs/*. There's typically one input file per problem setup file.

Submodules

• parthenon asynchronous tasking and block-AMR infrastructure
• singularity-eos provides performance-portable equations of state and PTE solvers
• singularity-opac provides performance-portable opacities and emissivities
• Kokkos provides performance portable shared-memory parallelism. It allows our loops to be CUDA, OpenMP, or something else. By default we use the Kokkos shipped with parthenon.

External (Required)

• cmake for building

Optional

• hdf5 for output
• MPI for distributed memory parallelism
• python3 for visualization

Clang-format

We use clang format for code cleanliness. The current version of clang-format is pinned to clang-format-12, however, you can try formatting with other versions at your own risk.

You can format all files in git history automatically by calling scripts/bash/format.sh from anywhere within the Phoebus repo (but outside of submodules).

You can specify which clang-format you use in the script with the CFM environment variable. For example:

CFM=clang-format-12 ./scripts/bash/format.sh

Copyright

© 2021. Triad National Security, LLC. All rights reserved. This program was produced under U.S. Government contract 89233218CNA000001 for Los Alamos National Laboratory (LANL), which is operated by Triad National Security, LLC for the U.S. Department of Energy/National Nuclear Security Administration. All rights in the program are reserved by Triad National Security, LLC, and the U.S. Department of Energy/National Nuclear Security Administration. The Government is granted for itself and others acting on its behalf a nonexclusive, paid-up, irrevocable worldwide license in this material to reproduce, prepare derivative works, distribute copies to the public, perform publicly and display publicly, and to permit others to do so.