Line data Source code
1 : !--------------------------------------------------------------------------------------------------!
2 : ! CP2K: A general program to perform molecular dynamics simulations !
3 : ! Copyright 2000-2025 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
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