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Description:

blond 2.1.11

Beam Longitudinal Dynamics Code (BLonD)
Copyright Notice
Copyright 2019 CERN. This software is distributed under the terms of the
GNU General Public Licence version 3 (GPL Version 3), copied verbatim in
the file LICENCE.txt. In applying this licence, CERN does not waive the
privileges and immunities granted to it by virtue of its status as an
Intergovernmental Organization or submit itself to any jurisdiction.
Description
CERN code for the simulation of longitudinal beam dynamics in
synchrotrons.
Useful Links
Repository: https://gitlab.cern.ch/blond/BLonD
Documentation: https://blond-code.docs.cern.ch/
Project website: http://blond.web.cern.ch
Installation
Dependencies

Python 3.8 or above (Anaconda is recommended).
(Optional) For better performance, a C++ (e.g. gcc, icc, clang, etc) compiler with C++11 support.

(Optional) C++ compiler installation instructions
Windows

Download the latest mingw-w64 using this link:
https://winlibs.com/#download-release
Extract the downloaded zip/7-zip under e.g. C:\. You should now
see a directory C:\mingw64.
Add C:\mingw64\bin in the PATH Environment Variable. Here you can
see how to do this in Windows
XP/Vista/7/8/10/11.
To validate the correct setup of gcc, open a command prompt and
type: gcc --version. The first output line should contain the gcc
version you just installed.

Linux
Use your distribution's package manager to install the compiler of your choice. BLonD has been tested with: gcc (recommended), icc, and clang.
Installation Steps
Installing BLonD from PyPI.

Use the pip package manager and simply run:
pip install blond

Installing BLonD manually (advanced users/ developers).

Clone the repository (with git) or download and extract it.

(Optional) From within the BLonD directory run:
python blond/compile.py

See the complete list of optional command line arguments with:
python blond/compile.py --help

Then install BLonD in edit mode with:
pip install -e .

Confirm proper installation

A quick way to confirm the successfull installation is to run:
python -c "from blond import test; test()"

If you installed BLonD manually, you can in addition run the unittests with pytest. The pytest package has to be installed first with pip. :
pip install pytest
pytest -v unittests

Note that running all the unit-tests might take more than 20 minutes, depending on your system.

You may also run some of the example main files found in the __EXAMPLES directory:
python __EXAMPLES/main_files/EX_01_Acceleration.py
python __EXAMPLES/main_files/EX_02_Main_long_ps_booster.py
etc..

Performance Optimizations
BLonD contains three computational backends, sorted in order of better performance:

C++ backend (Supports multi-threading and vectorization)
Numba backend (Supports multi-threading and vectorization)
Python-only backend (No multi-threading or vectorization)

The performance order also defines the order in which the backends will be used. If the C++ blond libary has been compiled, then the C++ backend will be used. Otherwise, if the numba package is installed, the numba backend will be used. Finally, if neither condition is met, the python-only backend will be used.
To use the Numba backend, you simply need to install the numba package with pip:
pip install numba

To use the C++ backend, follow the instructions provided in the section Installing BLonD manually.
In addition you may want to:

Use the multi-threaded blond C++ backend:
python blond/compile.py --parallel

Enable processor specific compiler optimizations:
python blond/compile.py --parallel --optimize

If you are test-case is calling the synchrotron radiation tracking method, you can accelerate it by using the Boost library. To do so you have to:

Download Boost: https://www.boost.org/. Let's say the version
you downloaded is boost_1_70.
Extract it, let's say in /user/path/to/boost_1_70.
Pass the boost installation path when compiling BLonD:
python blond/compile.py --boost=/user/path/to/boost_1_7_70

Check the following section about the FFTW3 library.

All the above can be combined, i.e.:
python blond/compile.py --parallel --optimize --boost=...

Changing the floating point number datatype
By default BLonD uses double precision calculations (float64). To change to single precision for faster calculations, in the beginning of your mainfile you will have to add the following code lines:
from blond.utils import bmath as bm
bm.use_precision('single')

Use the FFTW3 library for the FFTs
So far only the rfft(), irfft() and fftfreq() routines are
supported. fft_convolve() to be added soon.

Windows:

Download and unzip the pre-compiled FFTW3 library. Link:
ftp://ftp.fftw.org/pub/fftw/fftw-3.3.5-dll64.zip

Copy the libfftw3-3.dll under your python's distribution
directory.

Run the blond/compile.py with the flag --with-fftw.

If the FFTW3 library is not installed in one of the default
directories, use the --with-fftw-lib and --with-fftw-header
to point to the directories where the shared library and header
files are stored.

To use the supported routines, you need to call the function
use_fftw() from bmath.py:
from blond.utils import bmath as bm
bm.use_fftw()
...
bm.rfft(...)
bm.irfft(...)
bm.rfftfreq(...)

Linux:

Download and compile the FFTW3 library. Link:
http://www.fftw.org/fftw-3.3.8.tar.gz

Run the blond/compile.py with the flag: --with-fftw.

If the FFTW3 library is not installed in one of the default
directories, use the --with-fftw-lib and --with-fftw-header
to point to the directories where the shared library and header
files are stored.

Optionally, you can enable one of the flags --with-fftw-omp or
--with-fftw-threads to use the multithreaded FFTs.

To use the supported routines, you need to call the function
use_fftw() from bmath.py:
from blond.utils import bmath as bm
bm.use_fftw()
...
bm.rfft(...)
bm.irfft(...)
bm.rfftfreq(...)

Using the multi-node (MPI) implementation
Set-up Instructions

Add the following lines in your ~/.bashrc, then source it:
# Environment variables definitions
export LD_LIBRARY_PATH="$HOME/install/lib"
export INSTALL_DIR="$HOME/install"
export BLONDHOME="$HOME/git/BLonD"

# User aliases
alias mysqueue="squeue -u $USER"
alias myscancel="scancel -u $USER"
alias mywatch="watch -n 30 'squeue -u $USER'"

# Module loads
module load compiler/gcc7
module load mpi/mvapich2/2.3

Download and install anaconda3:
cd ~
mkdir -p ~/downloads
cd downloads
wget https://repo.continuum.io/archive/Anaconda3-2018.12-Linux-x86_64.sh
bash Anaconda3-2018.12-Linux-x86_64.sh -b -p $HOME/install/anaconda3

Download and install fftw3 (with the appropriate flags):
cd ~
mkdir -p ~/downloads
cd downloads
wget http://www.fftw.org/fftw-3.3.10.tar.gz
tar -xzvf fftw-3.3.10.tar.gz
cd fftw-3.3.10
./configure --prefix=$HOME/install/ --enable-openmp --enable-single --enable-avx --enable-avx2 --enable-fma --with-our-malloc --disable-fortran --enable-shared
make -j4
make install
./configure --prefix=$HOME/install/ --enable-openmp --enable-avx --enable-avx2 --enable-fma --with-our-malloc --disable-fortran --enable-shared
make -j4
make install

install mpi4py with pip:
pip install mpi4py

clone this repo, compile the library and link with fftw3_omp
cd ~
mkdir -p git
cd git
git clone --branch=master https://github.com/blond-admin/BLonD.git
cd BLonD
python blond/compile.py -p --with-fftw --with-fftw-threads --with-fftw-lib=$INSTALL_DIR/lib --with-fftw-header=$INSTALL_DIR/include

adjust your main file as needed (described bellow).

example scripts to setup and run a parameter scan in the HPC Slurm
cluster: https://cernbox.cern.ch/index.php/s/shqtotwyn4rm8ws

Changes required in the main file for MPI

This statements in the beginning of the script:
from blond.utils import bmath as bm
from blond.utils.mpi_config import WORKER, mpiprint
bm.use_mpi()

After having initialized the beam and preferably just before the
start of the main loop:
# This line splits the beam coordinates equally among the workers.
beam.split()

If there is code block that you want it to be executed by a single
worker only, you need to surround it with this if condition:
if WORKER.is_master:
foo()
...

If you need to re-assemble the whole beam back to the master worker
you need to run:
beam.gather()

Finally, in the end of the simulation main loop, you can terminate
all workers except from the master with:
WORKER.finalize()

To run your script, you need to pass it to mpirun or
mpiexec. To spawn P MPI processes run:
mpirun -n P python main_file.py

For more examples have a look at the __EXAMPLES/mpi_main_files/
directory.

Using the GPU backend
Setup Instructions

Install CUDA: https://developer.nvidia.com/cuda-downloads

Install the CuPy library:
https://docs.cupy.dev/en/stable/install.html

To verify your installation open a python terminal and execute the
following script
import cupy as cp
import numpy as np
a = cp.array(np.zeros(1000,np.float64))

To compile the CUDA files execute blond/compile.py and add the flag
--gpu. The Compute Capability of your GPU will be automatically
detected:
python blond/compile.py --gpu

Changes required in the main file for GPU

Right before your main loop you need to add:
from blond.utils import bmath as bm
# change some of the basic functions to their GPU equivalent
bm.use_gpu()

Also for every object you are using in your main loop that is in the
following list:

GPU objects

Beam

Profile

RingAndRFTracker

TotalInducedVoltage

InducedVoltageTime

InducedVoltageFreq

InductiveImpedance

InducedVoltageResonator

RFStation

BeamFeedback

you need to call their to_gpu() method. The following is a typical
example from the __EXAMPLES/gpu_main_files/EX_01_Acceleration.py
mainfile.
# Define Objects
beam = Beam(ring, N_p, N_b)
profile = Profile(beam, CutOptions(n_slices=100),
FitOptions(fit_option='gaussian'))
# Initialize gpu
beam.to_gpu()
profile.to_gpu()

If an object of this list has a reference inside a different one you
don't need to use the to_gpu() for the referenced object. In the
previous example, we don't need to call beam.to_gpu() since beam is
referenced inside the profile. The same would apply in a
TotalInducedVoltage object and the objects in its
induced_voltage_list.

Developers

Simon Albright (simon.albright (at) cern.ch)
Theodoros Argyropoulos (theodoros.argyropoulos (at) cern.ch)
Konstantinos Iliakis (konstantinos.iliakis (at) cern.ch)
Ivan Karpov (ivan.karpov (at) cern.ch)
Alexandre Lasheen (alexandre.lasheen (at) cern.ch)
Juan Esteban Muller (JuanF.EstebanMuller (at) ess.eu)
Danilo Quartullo (danilo.quartullo (at) cern.ch)
Joel Repond (joel (at) repond.ch)
Markus Schwarz (markus.schwarz (at) kit.edu)
Helga Timko (Helga.Timko (at) cern.ch)

Structure

the folder __EXAMPLES contains several main files which show how
to use the principal features of the code;
the __doc folder contains the source files for the documentation
on-line;
the various packages which constitute the code are under the blond
directory;
blond/compile.py is needed to compile all the C++ files present in
the project; this file should be run once before launching any
simulation. The compiler C++ GCC (at least version 4.8) is
necessary.
WARNINGS.txt contains useful information related to code usage.