Section FM_DIAG_SETTINGS

• This section defines a set of heuristic rules which are used to calculate the optimal number of CPUs, M, needed to diagonalize a full matrix distributed on N processors (FM type). If M < N, the matrix is redistributed onto M processors before it is diagonalized. The optimal value is calculate according to M = ((K+a*x-1)/(a*x))*a, where K is the size of the matrix, and {a, x} are integers defined below. The default values have been selected based on timings on a Cray XE6. Supports diagonalization libraries SL and ELPA (see keyword ELPA_FORCE_REDISTRIBUTE).

• Section path: CP2K_INPUT / GLOBAL / FM_DIAG_SETTINGS

• This section cannot be repeated.

• Subsections

  • none

• Keywords

  • ELPA_FORCE_REDISTRIBUTE
  • PARAMETER_A
  • PARAMETER_X
  • PRINT_FM_REDISTRIBUTE

• Keyword descriptions

  ELPA_FORCE_REDISTRIBUTE
  	ELPA_FORCE_REDISTRIBUTE {Logical}
  	Controls how to perform redistribution when ELPA is used for diagonalization. By default, matrices are redistributed only to prevent crashes in the ELPA library which happens when the original matrix is distributed over too many processors. By turning on this keyword, redistribution is always performed using the defined rules.
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .TRUE.

  PARAMETER_A
  	PARAMETER_A {Integer}
  	Parameter used for defining the rule which determines the optimal number of CPUs needed to diagonalize a full distributed matrix. The optimal number of CPUs will be an integer multiple of this variable.
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 4

  PARAMETER_X
  	PARAMETER_X {Integer}
  	Parameter used for defining the rule which determines the optimal number of CPUs needed to diagonalize a full distributed matrix. The optimal number of CPUs will be roughly proportional to this value.
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 60

  PRINT_FM_REDISTRIBUTE
  	PRINT_FM_REDISTRIBUTE {Logical}
  	Controls printing of information related to this section. For each diagonalized matrix, prints the size of the matrix, the optimal number of CPUs, as well as notifies if the matrix was redistributed. Useful for testing.
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .FALSE.