mpi_utilities Module Reference

Numerical utilities related to MPI. More...

Interfaces and Types
interface	get_ser_var
	Gather parallel variable in serial version on group master. More...
interface	get_ghost_arr
	Fill the ghost regions in an array. More...
interface	broadcast_var
	Wrapper function to broadcast a single variable using MPI. More...

Functions/Subroutines
integer function, public	redistribute_var (var, dis_var, lims, lims_dis)
	Redistribute variables according to new limits.
integer function, public	wait_mpi ()
	Wait for all processes, wrapper to MPI barrier.
integer function, public	lock_req_acc (lock, blocking)
	Request access to lock of a BL (blocking) or optionally a NB (non-blocking) type.
integer function, public	lock_return_acc (lock)
	Returns access to a lock.
integer function, public	lock_wl_change (wl_action, blocking, lock_loc, wl, ranks)
	Adds, removes or sets to active a rank from the waiting list for a lock and returns the lock waiting list:
character(len=max_str_ln) function, public	lock_header (lock_loc)
	Returns the header for lock debug messages.

Variables
logical, public	debug_lock = .false.
	print debug information about lock operations
integer, public	n_waits = 0
	number of waits

Detailed Description

Numerical utilities related to MPI.

This includes a lock system, which can be both BL (blocking) or NB (non-blocking). It is based on the implementation of an MPI-IO atomic mode without file support, described in [13].

See also

See mpi_vars.

The reason for this was the fact that using a simple lock file can lead to crashes.

Note

A downside of this method is that in some rare cases a deadlock may occur as the master process, which contains the shared variable with a window that other processes may use, is idle and waiting, whereas the others are still performing lock options. As the master is idle and waiting, its MPI asynchronous communication is not performed. To remedy this, just call wait_MPI() after procedures where lock operations are performed.

Function/Subroutine Documentation

lock_header()

character(len=max_str_ln) function, public mpi_utilities::lock_header

(

type(lock_type), intent(in)

lock_loc

)

Returns the header for lock debug messages.

Note

Debug version only

Parameters

[in]

lock_loc

lock

Definition at line 1216 of file MPI_utilities.f90.

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lock_req_acc()

integer function, public mpi_utilities::lock_req_acc	(	type(lock_type), intent(inout)	lock,
		logical, intent(in), optional	blocking )

Request access to lock of a BL (blocking) or optionally a NB (non-blocking) type.

Note

Based on [13].

Returns

ierr

Definition at line 764 of file MPI_utilities.f90.

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lock_return_acc()

integer function, public mpi_utilities::lock_return_acc

(

type(lock_type), intent(inout)

lock

)

Returns access to a lock.

The blocking property has been set when requesting the lock.

Note

Based on [13].

Returns

ierr

Definition at line 871 of file MPI_utilities.f90.

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lock_wl_change()

integer function, public mpi_utilities::lock_wl_change	(	integer, intent(in)	wl_action,
		logical, intent(in)	blocking,
		type(lock_type), intent(inout)	lock_loc,
		integer, dimension(:), intent(inout), allocatable	wl,
		integer, dimension(:), intent(in), optional	ranks )

Adds, removes or sets to active a rank from the waiting list for a lock and returns the lock waiting list:

Actions:

• wl_action = 0: remove
• wl_action = 1: add
• wl_action = 2: active

Or negative equivalents for non-blocking (NB) procs.

Optionally, the rank(s) of the process for which to perform this action can be passed. This is useful for doing the same action on multiple processes.

Note

Based on [13].

Debug version only

Returns

ierr

Parameters

[in]	wl_action	action to perform
[in]	blocking	the ranks to be changed are blocking
[in,out]	lock_loc	lock
[in,out]	wl	waiting list
[in]	ranks	rank(s) for which to perform option

Definition at line 1109 of file MPI_utilities.f90.

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redistribute_var()

integer function, public mpi_utilities::redistribute_var	(	real(dp), dimension(:), intent(in)	var,
		real(dp), dimension(:), intent(inout)	dis_var,
		integer, dimension(2), intent(in)	lims,
		integer, dimension(2), intent(in)	lims_dis )

Redistribute variables according to new limits.

Parameters

[in]	var	parallel vector
[in,out]	dis_var	redistributed vector
[in]	lims	indices of parallel vector
[in]	lims_dis	indices of redistributed parallel vector

Definition at line 329 of file MPI_utilities.f90.

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wait_mpi()

integer function, public mpi_utilities::wait_mpi

Wait for all processes, wrapper to MPI barrier.

Returns

ierr

Definition at line 743 of file MPI_utilities.f90.

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Variable Documentation

debug_lock

logical, public mpi_utilities::debug_lock = .false.

print debug information about lock operations

Note

Debug version only

Definition at line 40 of file MPI_utilities.f90.

n_waits

integer, public mpi_utilities::n_waits = 0

number of waits

Note

Debug version only

Definition at line 41 of file MPI_utilities.f90.