Numerical utilities related to MPI. More...

Interfaces and Types
interface	broadcast_var
	Wrapper function to broadcast a single variable using MPI. More...

interface	get_ghost_arr
	Fill the ghost regions in an array. More...

interface	get_ser_var
	Gather parallel variable in serial version on group master. More...

Functions/Subroutines
integer function, public	redistribute_var (var, dis_var, lims, lims_dis)
	Redistribute variables according to new limits. More...

integer function, public	wait_mpi ()
	Wait for all processes, wrapper to MPI barrier. More...

integer function, public	lock_req_acc (lock, blocking)
	Request access to lock of a BL (blocking) or optionally a NB (non-blocking) type. More...

integer function, public	lock_return_acc (lock)
	Returns access to a lock. More...

logical function	wl_empty (wl, proc_type, next_procs)
	Decides whether a waiting list is empty. More...

integer function	lock_notify (lock_loc, rec_rank)
	Notifies a rank that they can get the lock. More...

integer function	lock_get_notified (lock_loc)
	Get notified that the rank can get the lock. More...

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: More...

character(len=max_str_ln) function, public	lock_header (lock_loc)
	Returns the header for lock debug messages. More...

Variables
logical, public	debug_lock = .false.
	print debug information about lock operations More...

integer, public	n_waits = 0
	number of waits More...

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_get_notified()

integer function mpi_utilities::lock_get_notified ( type(lock_type), intent(in) lock_loc )

Get notified that the rank can get the lock.

Note: Based on [13].

Returns: ierr

Parameters

[in] lock_loc lock

Definition at line 1063 of file MPI_utilities.f90.

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◆ 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 1217 of file MPI_utilities.f90.

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◆ lock_notify()

integer function mpi_utilities::lock_notify	(	type(lock_type), intent(in)	lock_loc,
		integer, intent(in)	rec_rank
	)

Notifies a rank that they can get the lock.

The signal sent is the rank + 1.

Note: Based on [13].

Returns: ierr

Parameters

[in]	lock_loc	lock
[in]	rec_rank	receiving rank

Definition at line 1031 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 765 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 872 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 1111 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 330 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 744 of file MPI_utilities.f90.

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◆ wl_empty()

logical function mpi_utilities::wl_empty	(	integer, dimension(:), intent(in)	wl,
		integer, dimension(:), intent(in)	proc_type,
		integer, dimension(:), intent(inout), optional, allocatable	next_procs
	)

Decides whether a waiting list is empty.

The type of process to find is indicated by an array of possible values.

See also: See lock_wl_change() for an explanation of the process type.

Additionally, for NB processes, the negative inverse of these values are used.

If the waiting list is not empty, the next process(es) can optionally be returned.

Note: Based on [13].

Returns: ierr

Parameters

[in]	wl	waiting list
[in]	proc_type	types of processes accepted
[in,out]	next_procs	next process(es) if not empty

Definition at line 985 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.

Interfaces and Types

Functions/Subroutines

Variables

Detailed Description

Function/Subroutine Documentation

◆ lock_get_notified()

◆ lock_header()

◆ lock_notify()

◆ lock_req_acc()

◆ lock_return_acc()

◆ lock_wl_change()

◆ redistribute_var()

◆ wait_mpi()

◆ wl_empty()

Variable Documentation

◆ debug_lock

◆ n_waits