GPU support for surface fluxes

[sriharshakandala]

The Climate Modeling Alliance

Software Design Issue 📜

Purpose

SurfaceFluxes.jl is required for the computation of boundary conditions for the atmosphere model. As such, GPU compatibility is a necessity. This issue defines pending tasks for GPU support.

Cost/Benefits/Risks

People and Personnel

@LenkaNovak @sriharshakandala @charleskawczynski @simonbyrne

Components

• UniversalFunctions.jl : Contains expressions for similarity and stability correction functions for use within the SurfaceFluxes.jl package.
• SurfaceFluxes.jl : Contains functions that compute physical properties at the lower boundary of an atmosphere simulation, using the Monin-Obukhov similarity theory(MOST). This includes fluxes of momentum, heat, moisture and scale variables for use in the MOST.

Inputs

Results and Deliverables

• GPU compatible SurfaceFluxes.jl package, tested in both single and double precision configurations.

Task Breakdown And Schedule

• Set up correct dependencies for CUDA.
• Identify failing tests
• Update test_profiles.jl to specialize based on device.
• Update test_convergence.jl to specialize based on device.
• Update test_universal_functions.jl to specialize based on device.
• PR Enable GPU tests #86. GPU Tests are currently disabled. These need to be brought back online-
  

  SurfaceFluxes.jl/test/runtests.jl

  Lines 24 to 34 in 48b25f1

  	# FIXME: Refactor tests to work on GPUs as in `Thermodynamics.jl`
  	#if get(ARGS, 1, "Array") == "CuArray"
  	# using CUDA
  	# import CUDAKernels: CUDADevice
  	# ArrayType = CUDA.CuArray
  	# CUDA.allowscalar(false)
  	# device(::T) where {T <: CuArray} = CUDADevice()
  	#else
  	ArrayType = Array
  	device(::T) where {T <: Array} = CPU()
  	#end

• Documented, GPU compatible toolbox for surface flux calculations for use within ClimaAtmos.jl.

SDI Revision Log

9/11/2023: Moves all GPU specific items from other issues #83 # into #113
10/27/2023: Device specialisation not necessary -> current solution removes error print statements which is sufficient: the resulting issue is tracked in CliMA/ClimaAtmos.jl#2136

CC

[charleskawczynski]

Closed by #22.