Line data    Source code

       1             : !--------------------------------------------------------------------------------------------------!
       2             : !   CP2K: A general program to perform molecular dynamics simulations                              !
       3             : !   Copyright 2000-2024 CP2K developers group <https://cp2k.org>                                   !
       4             : !                                                                                                  !
       5             : !   SPDX-License-Identifier: GPL-2.0-or-later                                                      !
       6             : !--------------------------------------------------------------------------------------------------!
       7             : 
       8             : ! **************************************************************************************************
       9             : !> \brief Environment for NEGF based quantum transport calculations
      10             : !> \author Sergey Chulkov
      11             : ! **************************************************************************************************
      12             : 
      13             : MODULE negf_subgroup_types
      14             :    USE cp_blacs_env,                    ONLY: cp_blacs_env_create,&
      15             :                                               cp_blacs_env_release,&
      16             :                                               cp_blacs_env_type
      17             :    USE message_passing,                 ONLY: mp_comm_type,&
      18             :                                               mp_para_env_release,&
      19             :                                               mp_para_env_type
      20             :    USE negf_control_types,              ONLY: negf_control_type
      21             : #include "./base/base_uses.f90"
      22             : 
      23             :    IMPLICIT NONE
      24             :    PRIVATE
      25             : 
      26             :    CHARACTER(len=*), PARAMETER, PRIVATE :: moduleN = 'negf_subgroup_types'
      27             :    LOGICAL, PARAMETER, PRIVATE          :: debug_this_module = .TRUE.
      28             : 
      29             :    PUBLIC :: negf_subgroup_env_type, negf_sub_env_create, negf_sub_env_release
      30             : 
      31             : ! **************************************************************************************************
      32             : !> \brief Parallel (sub)group environment.
      33             : !> \par History
      34             : !>   * 06.2017 created [Sergey Chulkov]
      35             : ! **************************************************************************************************
      36             :    TYPE negf_subgroup_env_type
      37             :       !> number of parallel groups.
      38             :       !> If it is >1 then the global MPI communicator has actually been split into subgroups.
      39             :       !> All other components of the structure are always initialised regardless of the split status
      40             :       !> (they simply point to the corresponding global variables if no splitting has been made).
      41             :       INTEGER                                            :: ngroups = -1
      42             :       !> global MPI rank of the given processor. Local MPI rank can be obtained as para_env%mepos.
      43             :       !> Useful to find out the current group index by accessing the 'group_distribution' array.
      44             :       INTEGER                                            :: mepos_global = -1
      45             :       !> global MPI communicator
      46             :       TYPE(mp_comm_type)                                 :: mpi_comm_global = mp_comm_type()
      47             :       !> group_distribution(0:num_pe) : a process with rank 'i' belongs to the parallel group
      48             :       !> with index 'group_distribution(i)'
      49             :       INTEGER, DIMENSION(:), ALLOCATABLE                 :: group_distribution
      50             :       !> group-specific BLACS parallel environment
      51             :       TYPE(cp_blacs_env_type), POINTER                   :: blacs_env => NULL()
      52             :       !> group-specific MPI parallel environment
      53             :       TYPE(mp_para_env_type), POINTER                    :: para_env => NULL()
      54             :    END TYPE negf_subgroup_env_type
      55             : 
      56             : CONTAINS
      57             : 
      58             : ! **************************************************************************************************
      59             : !> \brief Split MPI communicator to create a set of parallel (sub)groups.
      60             : !> \param sub_env           parallel (sub)group environment (initialised on exit)
      61             : !> \param negf_control      NEGF input control
      62             : !> \param blacs_env_global  BLACS environment for all the processors
      63             : !> \param blacs_grid_layout BLACS grid layout
      64             : !> \param blacs_repeatable  BLACS repeatable layout
      65             : !> \par History
      66             : !>    * 06.2017 created [Sergey Chulkov]
      67             : ! **************************************************************************************************
      68           4 :    SUBROUTINE negf_sub_env_create(sub_env, negf_control, blacs_env_global, blacs_grid_layout, blacs_repeatable)
      69             :       TYPE(negf_subgroup_env_type), INTENT(out)          :: sub_env
      70             :       TYPE(negf_control_type), POINTER                   :: negf_control
      71             :       TYPE(cp_blacs_env_type), POINTER                   :: blacs_env_global
      72             :       INTEGER, INTENT(in)                                :: blacs_grid_layout
      73             :       LOGICAL, INTENT(in)                                :: blacs_repeatable
      74             : 
      75             :       CHARACTER(LEN=*), PARAMETER :: routineN = 'negf_sub_env_create'
      76             : 
      77             :       INTEGER                                            :: handle
      78             :       LOGICAL                                            :: is_split
      79             :       TYPE(mp_para_env_type), POINTER                    :: para_env_global
      80             : 
      81           4 :       CALL timeset(routineN, handle)
      82             : 
      83           4 :       CALL blacs_env_global%get(para_env=para_env_global)
      84           4 :       sub_env%mepos_global = para_env_global%mepos
      85           4 :       sub_env%mpi_comm_global = para_env_global
      86             : 
      87             :       ! ++ split mpi communicator if
      88             :       !    a) the requested number of processors per group > 0 (means that the split has been requested explicitly), and
      89             :       !    b) the number of subgroups is >= 2
      90           4 :       is_split = negf_control%nprocs > 0 .AND. negf_control%nprocs*2 <= para_env_global%num_pe
      91             : 
      92             :       IF (is_split) THEN
      93          12 :          ALLOCATE (sub_env%group_distribution(0:para_env_global%num_pe - 1))
      94             : 
      95           4 :          ALLOCATE (sub_env%para_env)
      96             :          CALL sub_env%para_env%from_split(comm=para_env_global, ngroups=sub_env%ngroups, &
      97           4 :                                           group_distribution=sub_env%group_distribution, subgroup_min_size=negf_control%nprocs)
      98             : 
      99             :          ! ++ create a new parallel environment based on the given sub-communicator)
     100           4 :          NULLIFY (sub_env%blacs_env)
     101             : 
     102             :          ! use the default (SQUARE) BLACS grid layout and non-repeatable BLACS collective operations
     103             :          ! by omitting optional parameters 'blacs_grid_layout' and 'blacs_repeatable'.
     104           4 :          CALL cp_blacs_env_create(sub_env%blacs_env, sub_env%para_env, blacs_grid_layout, blacs_repeatable)
     105             :       ELSE
     106           0 :          sub_env%para_env => para_env_global
     107           0 :          sub_env%ngroups = 1
     108             : 
     109           0 :          ALLOCATE (sub_env%group_distribution(0:para_env_global%num_pe - 1))
     110           0 :          sub_env%group_distribution(:) = 0
     111             : 
     112           0 :          sub_env%blacs_env => blacs_env_global
     113           0 :          CALL sub_env%blacs_env%retain()
     114             : 
     115           0 :          sub_env%para_env => para_env_global
     116           0 :          CALL sub_env%para_env%retain()
     117             :       END IF
     118             : 
     119           4 :       CALL timestop(handle)
     120           4 :    END SUBROUTINE negf_sub_env_create
     121             : 
     122             : ! **************************************************************************************************
     123             : !> \brief Release a parallel (sub)group environment.
     124             : !> \param sub_env    parallel (sub)group environment to release
     125             : !> \par History
     126             : !>    * 06.2017 created [Sergey Chulkov]
     127             : ! **************************************************************************************************
     128           4 :    SUBROUTINE negf_sub_env_release(sub_env)
     129             :       TYPE(negf_subgroup_env_type), INTENT(inout)        :: sub_env
     130             : 
     131             :       CHARACTER(LEN=*), PARAMETER :: routineN = 'negf_sub_env_release'
     132             : 
     133             :       INTEGER                                            :: handle
     134             : 
     135           4 :       CALL timeset(routineN, handle)
     136             : 
     137           4 :       CALL cp_blacs_env_release(sub_env%blacs_env)
     138           4 :       CALL mp_para_env_release(sub_env%para_env)
     139             : 
     140           4 :       IF (ALLOCATED(sub_env%group_distribution)) &
     141           4 :          DEALLOCATE (sub_env%group_distribution)
     142             : 
     143           4 :       sub_env%ngroups = 0
     144             : 
     145           4 :       CALL timestop(handle)
     146           4 :    END SUBROUTINE negf_sub_env_release
     147           0 : END MODULE negf_subgroup_types