tem_calc_imbalance Function

public function tem_calc_imbalance(myCost, comm, nProcs, isRoot) result(imbalance)

Evaluate the imbalance of all the processes by each rank.

Arguments

Type IntentOptional Attributes Name
real(kind=rk), intent(in) :: myCost

each process cpu cost. Basis to evaluate the imbalance
integer, intent(in) :: comm

MPI Communicator
integer, intent(in) :: nProcs

MPI Communicator
logical, intent(in) :: isRoot

Whether this rank is the root

Return Value real(kind=rk)

in percentage


Calls

proc~~tem_calc_imbalance~~CallsGraph proc~tem_calc_imbalance tem_calc_imbalance mpi_reduce mpi_reduce proc~tem_calc_imbalance->mpi_reduce proc~tem_horizontalspacer tem_horizontalSpacer proc~tem_calc_imbalance->proc~tem_horizontalspacer

Source Code

  function tem_calc_imbalance( myCost, comm, nProcs, isRoot ) result ( imbalance )
    ! ---------------------------------------------------------------------------
    !> each process cpu cost. Basis to evaluate the imbalance
    real(kind=rk), intent(in) :: myCost
    !> MPI Communicator
    integer, intent(in) :: comm, nProcs
    !> in percentage
    real(kind=rk) :: imbalance
    !> Whether this rank is the root
    logical, intent(in) :: isRoot
    ! ---------------------------------------------------------------------------
    ! computation cost over all processes
    real(kind=rk) :: totalCost, maxCost
    integer :: iErr ! error handle
    ! ---------------------------------------------------------------------------

    call mpi_reduce( myCost,   maxCost, 1, rk_mpi, mpi_max, 0, comm, iErr)
    call mpi_reduce( myCost, totalCost, 1, rk_mpi, mpi_sum, 0, comm, iErr)

    imbalance = -9999._rk
    ! the value range of imbalance is [100%, nProcs]
    ! The smaller the value, the better the balance is
    if ( isRoot ) then
      totalCost = totalCost/dble(nProcs)
      imbalance = maxCost / totalCost * 100

      call tem_horizontalSpacer(fUnit=logUnit(5))
      write(logUnit(3),"(A)")         ' Load balance evaluation:'
      write(logUnit(3),"(A,F10.2,A)")   '  max CPU cost:', maxCost, ' (s)'
      write(logUnit(3),"(A,F10.2,A)")   '  ave CPU cost:', totalCost, ' (s)'
      write(logUnit(3),"(A,F10.2,A)") ' imbalance (i.e. max/ave):', imbalance, '%'
      call tem_horizontalSpacer(fUnit=logUnit(5))
    end if

  end function tem_calc_imbalance