BLonD code development meeting



Video conferencing only

Pre-Christmas meeting!!


Mihály: python3.8 compatibility of the .dll

  • pull request changing for import of .dll
  • related to windows dll with python3.8 or python3.9
    • winmode=0 needs to be specified (not winmode=None as in docs)
  • cpp library added to search paths for PATH
  • Works with lxplus python3.8
  • Kostis: add to appveyor and travis python 3.8
  • Simon: some coding comments
  • Markus: blond and macos 14? programmes can only access their own folders
    • Ivan works on macos big sur

Alex: gcc version we were using - no updates anymore since a while

  • Should clarify which version to use in the future

Kostis: pull requests

  • Fast resonator: openMP directives put back
    • Alex: zero frequency check
    • Simon: does if break the vectorisation?
  • Fix issue with beam split: only used in MPI version
    • random/fast option of coordinate distribution
    • randomisation fixed

Helga: BLonD publication

  • Please log in and put your names on the parts you volunteer to revise
  • Add new paragraphs on new developments as you see fit
  • Markus: revise induced voltage

Alex & Kostis: MPI usage for PS end-to-end simulations

Application: e.g. blow-up in ramp

  • W/o intensity effects, chopped simulations into chuncks and transferred profiles
  • Bunch position and bunch length look similar to development in the machine
  • Difficulty in including impedance model
    • Several profiles with different bin sizes? difficult to implement, needs tracking several times
    • Adapt bin size to bunch length? requires to adapt impedance
    • Keep a fixed bin size? large no of particles needed -> with slurm we can do that!
  • Can save time on updating only parts of the impedance model
    • needed as impedance changes with energy
  • MPI: each worker can work on a frequency range of the impedance model
    • scatter does not necessarily scatter in order of frequency -> use fast resonator function
    • can use multiprocessing functions: for python functions (where no C++ function existing)
    • pool.starmap - > giving every function the arguments that need to be used
  • python multiprocessing: small speed-up for few points, but x2 for large amounts of points
  • MPI gave significant speed-up, up to 5.6x
  • 480 M particles on SLURM can be calculated with 280 ms/turn -> 2.5 days for full simulation
  • Simon: GPU could give benefits!
    • Panagiotis: preparing pull request
    • Kostis: can test MPI-over-GPU with Alex' main file
  • Ivan: multi-turn wake ->  N. Mounet's thesis p. 50 alternative method for long-range wakes

Simon: data types

Datatype object in BLonD-common

  • self-identify and self-interpolate information
  • inherit from numpy array
  • initialise with *args
    • removes ambiguity of input shape
    • 0D: single value
    • 1D: turn-by-turn data
    • 2D: time, data
  • output size is pre-defined, with n_elements in the output
  • class name tells what the contents is (momentum, voltage etc.)
    • units and information (rms, fwhm) can be added
  • time or turn data, either one or the other
  • transformation between e.g. momentum and energy
    • passing arguments needed
    • self-identifies, too
  • structure: core handles base class and numpy class
    • ring_programs, rf_programs etc for specific functions
    • inheritance structure
      • eases to define lower-level definitions
  • todo: save and load functionality
    • with units and definitions
  • Alex: need to agree on reshaping and keep it slide 10
    • for inheritance, can simply define new variables like beta -> to keep in mind for integration in BLonD
There are minutes attached to this event. Show them.
    • 10:30 10:40
      News 10m
      • python 3.8 compatibility
      Speakers: Alexandre Lasheen (CERN) , Giulia Papotti (CERN) , Heiko Damerau (CERN) , Ivan Karpov (CERN) , Konstantinos Iliakis (CERN) , Luis Eduardo Medina Medrano (CERN) , Markus Schwarz (KIT) , Panagiotis Tsapatsaris (NTUA) , Simon Albright (CERN) , Theodoros Argyropoulos (CERN)
    • 10:40 10:50
      User feedback on MPI implementation 10m
      Speaker: Alexandre Lasheen (CERN)
    • 10:50 11:10
      Data types usage 20m
      Speaker: Simon Albright (CERN)
    • 11:10 11:30
      BLonD/BLonD common integration 20m
      • Pull request for RF
      • Discussion on next steps
      Speakers: Alexandre Lasheen (CERN) , Helga Timko (CERN) , Konstantinos Iliakis (CERN) , Simon Albright (CERN)