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@MASTERSTHESIS{Vogelsang:888549,
      author       = {Vogelsang, Jan},
      title        = {{A} concept study of a flexible asynchronous scheduler for
                      dynamic {E}arth {S}ystem {M}odel components on heterogeneous
                      {HPC} systems},
      school       = {FH Aachen},
      type         = {Bachelorarbeit},
      reportid     = {FZJ-2020-05013},
      pages        = {68},
      year         = {2020},
      note         = {Bachelorarbeit, FH Aachen, 2020},
      abstract     = {Climate change is presenting one of the biggest challenges
                      for mankind as recent developments have shown. Since 1990,
                      the global temperature increased by almost 1°C and earth
                      system model projections indicate that temperatures will
                      raise another two to four degrees by 2100 unless drastic
                      measures are taken quickly to avoid greenhouse gas
                      emissions. Since several decades, scientists have
                      constructed numerical models to simulate weather and
                      climate. Such models describe physical and biogeochemical
                      processes in the atmosphere, the ocean, the land surface and
                      the cryosphere and are thus called earth system models
                      (ESM).In that same period of time the computing power of the
                      worlds largest supercomputers has rocketed upwards as
                      today’s fastest supercomputer offers 170.000 times more
                      computing power than the fastest one 20 years ago. By
                      utilizing this enormouscomputing power, it has become
                      possible to simulate high-resolution weather and climate
                      models that are capable of predicting extreme events with
                      reasonable accuracy.As the computing power of modern
                      supercomputers increases rapidly, so does the complexity of
                      the underlying architecture. Specialized nodes equipped with
                      new technology like graphical processing units allow a
                      massive reduction of computing time for many problem
                      classes, but do also introduce the challenge to work with a
                      heterogeneous architecture. ESMs were hitherto designed for
                      homogeneous architectures based central processing units.
                      Along with the increased computational demands ofESMs, the
                      amount of generated data does as well, leading to the
                      phenomenon that the cost of data movement starts to dominate
                      the overall cost of computation. Any new programming
                      paradigm for ESMs must therefore try to minimize massive
                      data transfers, e.g. by utilizing data locality as it will
                      be demonstrated in this work.Facing the challenges of modern
                      supercomputer architecture and the need for more flexible
                      and modular models, completely new programming concepts are
                      needed, as demonstrated by the Helmholtz project Pilot Lab
                      Exascale Earth System Modelling(PL-ExaESM) in which context
                      this work has been conducted.As a potential solution for
                      these challenges a new, asynchronous scheduling method for
                      modular ESM components has been tested in a sandbox
                      environment and evaluated with respects to performance,
                      scalability and flexibility. Asynchronous scheduling allows
                      for a better exploitation of the heterogeneous resources of
                      a modern HPC system. Through careful consideration of data
                      flow paths across the coupled pseudoESM components, data
                      movement could be reduced by more than $50\%$ compared to a
                      traditional sequential ESM workflow.Furthermore, running
                      different example workflows showed a high efficiency gain
                      for complex workflows when increasing the number of nodes
                      used for computation. The results obtained here are
                      promising, however not yet sufficient to propose
                      asynchronous scheduling as the one new ESM paradigm to be
                      used for upcoming exascale earth system modelling. Further
                      development and investigation following the approach
                      proposed in this work is required to evaluate the usability
                      on different architectures and comparing it to different
                      approaches meeting the introduced challenges of modern ESM
                      development.},
      cin          = {JSC},
      cid          = {I:(DE-Juel1)JSC-20090406},
      pnm          = {512 - Data-Intensive Science and Federated Computing
                      (POF3-512)},
      pid          = {G:(DE-HGF)POF3-512},
      typ          = {PUB:(DE-HGF)2},
      url          = {https://juser.fz-juelich.de/record/888549},
}