Initialize an IOSystem

Create a new IO System, designating numbers of I/O and computation tasks in Fortran. More...

Functions/Subroutines
subroutine	piolib_mod::init_intracom (comp_rank, comp_comm, num_iotasks, num_aggregator, stride, rearr, iosystem, base, rearr_opts)
	Rearranger methods. More...
subroutine	piolib_mod::init_intercom (iosystem, incomm, procs_per_component, comp_proc_list, io_proc_list, rearranger, comp_comm, io_comm)
subroutine	piolib_mod::init_intercom_from_comms (iosystem, world_comm, comp_comms, io_comm, rearranger)

Detailed Description

Create a new IO System, designating numbers of I/O and computation tasks in Fortran.

Use the Fortran generic function PIO_init() to initialize the IO System. The PIO_init() function will call init_intracom().

This code from examples/f03/examplePio.F90 demonstrates how to initialize the IO system for intracom mode.

call PIO_init(this%myRank,      & ! MPI rank
    mpi_comm_world,             & ! MPI communicator
    this%niotasks,              & ! Number of iotasks (ntasks/stride)
    this%numAggregator,         & ! number of aggregators to use
    this%stride,                & ! stride
    pio_rearr_subset,           & ! do not use any form of rearrangement
    this%pioIoSystem,           & ! iosystem
    base=this%optBase)            ! base(optional argument)

Function/Subroutine Documentation

init_intercom()

subroutine piolib_mod::init_intercom	(	type(iosystem_desc_t), dimension(:), intent(out)	iosystem,
		integer, intent(in)	incomm,
		integer, dimension(:), intent(in)	procs_per_component,
		integer, dimension(:,:), intent(in)	comp_proc_list,
		integer, dimension(:), intent(in)	io_proc_list,
		integer, intent(in)	rearranger,
		integer, dimension(:), intent(out)	comp_comm,
		integer, intent(out)	io_comm
	)

Initialize the pio subsystem. This is a collective call. Input parameters are read on comp_rank=0 values on other tasks are ignored. This variation of PIO_init sets up a distinct set of tasks to handle IO, these tasks do not return from this call. Instead they go to an internal loop and wait to receive further instructions from the computational tasks.

Parameters

iosystem	An array of type iosystem_desc_t and size component_count
incomm	A MPI communicator which includes all tasks in the call
procs_per_component	An integer array of tasks per computational component
comp_proc_list	A 2d array of all ranks in incomm for each computational component
io_proc_list	An array of all io ranks in incomm
rearranger	The rearranger to use (currently only PIO_BOX_REARR)
comp_comm	On output the MPI comm for each computational component (MPI_COMM_NULL on tasks not in this component)
io_comm	On output the MPI comm for the IO component (MPI_COMM_NULL on tasks not in io component)

Author

Jim Edwards

init_intercom_from_comms()

subroutine piolib_mod::init_intercom_from_comms	(	type(iosystem_desc_t), dimension(:), intent(out)	iosystem,
		integer, intent(in)	world_comm,
		integer, dimension(:), intent(in)	comp_comms,
		integer, intent(in)	io_comm,
		integer, intent(in)	rearranger
	)

Initialize the pio subsystem. This is a collective call. Input parameters are read on comp_ranks=0 and io_rank=0 values on other tasks are ignored. This variation of PIO_init uses tasks in io_comm to handle IO, these tasks do not return from this call. Instead they go to an internal loop and wait to receive further instructions from the computational tasks.

Parameters

iosystem	An array of type iosystem_desc_t and size component_count
world_comm	A MPI communicator which includes all tasks in the call
comp_comms	On input the MPI comm for each computational component (MPI_COMM_NULL on tasks not in this component)
io_comm	On input the MPI comm for the IO component (MPI_COMM_NULL on tasks not in io component)
rearranger	The rearranger to use (currently only PIO_BOX_REARR)

Author

Jim Edwards

init_intracom()

subroutine piolib_mod::init_intracom	(	integer(i4), intent(in)	comp_rank,
		integer(i4), intent(in)	comp_comm,
		integer(i4), intent(in)	num_iotasks,
		integer(i4), intent(in)	num_aggregator,
		integer(i4), intent(in)	stride,
		integer(i4), intent(in)	rearr,
		type (iosystem_desc_t), intent(out)	iosystem,
		integer(i4), intent(in), optional	base,
		type (pio_rearr_opt_t), intent(in), optional, target	rearr_opts
	)

Rearranger methods.

Initialize the pio subsystem. This is a collective call. Input parameters are read on comp_rank=0 values on other tasks are ignored. This variation of PIO_init locates the IO tasks on a subset of the compute tasks.

Parameters

comp_rank	mpi rank of each participating task,
comp_comm	the mpi communicator which defines the collective.
num_iotasks	the number of iotasks to define.
num_aggregator	the mpi aggregator count
stride	the stride in the mpi rank between io tasks.
rearr	- PIO_rearr_none : Do not use any form of rearrangement PIO_rearr_box : Use a PIO internal box rearrangement PIO_rearr_subset : Use a PIO internal subsetting rearrangement
iosystem	a derived type which can be used in subsequent pio operations (defined in PIO_types).
base	optional argument can be used to offset the first io task. Since this is an MPI task number, it is zero-based (the first task is 0). The default base is task 0.
rearr_opts	the rearranger options.

Author

Jim Edwards