qimpy.mpi.ProcessGrid

class ProcessGrid(comm, dim_names, shape=None)

Bases: object

Process grid of shape dimensions over communicator comm. Any -1 entries in shape are undetermined and will be resolved after the number of tasks split along that dimension are set using provide_n_tasks. Subsequently, use get_comm to get arbitrary hyperplane communicators that connect processes whose index only varies along specified subsets of dimensions.

Parameters:

comm (Comm)
dim_names (str)
shape (ndarray)

__init__(comm, dim_names, shape=None)

Parameters:

comm (Comm)
dim_names (str)
shape (Sequence[int] | None)

Return type:

None

Methods

`__init__`
`get_comm`	Get communicator for a hyper-plane spanning dim_names.
`provide_n_tasks`	Provide task count for a process grid dimension named dim_name.

Attributes

`comm`	Overall communicator within which grid is set-up.
`n_procs`	Total number of processes in grid.
`i_proc`	Overall rank of current process in grid.
`dim_names`	Each character (must be unique) names a dimension.
`shape`	Grid dimensions.

get_comm(dim_names)

Get communicator for a hyper-plane spanning dim_names. The resulting communicator will connect processes whose index in the process grid only varies along dimensions within dim_names. Dimensions before and including those in dim_names must be known, except when dim_names is a contiguous block of dimensions whose product can be determined now based on other dimensions.

Parameters:: dim_names (str)
Return type:: Comm

provide_n_tasks(dim_name, n_tasks)

Provide task count for a process grid dimension named dim_name. If that dimension is undetermined (-1), set it to a suitable value that is compatible with the total processes, any other known dimensions, and with splitting n_tasks tasks with reasonable load balancing over this dimension.

Parameters:

dim_name (str) – Name of dimension (single charcater) to provide n_tasks for.
n_tasks (int) – Number of tasks available to split on this dimension of the process grid, used for setting dimension to ensure reasonable load balancing.

Return type:

None

comm: Comm: Overall communicator within which grid is set-up.

dim_names: str: Each character (must be unique) names a dimension.

i_proc: int: Overall rank of current process in grid.

n_procs: int: Total number of processes in grid.

shape: ndarray: Grid dimensions. Unresolved dimensions are -1.