Initialize a Decomposition

Intiailize a decomposition of data into distributed arrays in C. More...

Functions
int	PIOc_InitDecomp (int iosysid, int pio_type, int ndims, const int *gdimlen, int maplen, const PIO_Offset *compmap, int *ioidp, const int *rearranger, const PIO_Offset *iostart, const PIO_Offset *iocount)
	Initialize the decomposition used with distributed arrays. More...
int	PIOc_init_decomp (int iosysid, int pio_type, int ndims, const int *gdimlen, int maplen, const PIO_Offset *compmap, int *ioidp, int rearranger, const PIO_Offset *iostart, const PIO_Offset *iocount)
	Initialize the decomposition used with distributed arrays. More...
int	PIOc_InitDecomp_bc (int iosysid, int pio_type, int ndims, const int *gdimlen, const long int *start, const long int *count, int *ioidp)
	This is a simplified initdecomp which can be used if the memory order of the data can be expressed in terms of start and count on the file. More...

Detailed Description

Intiailize a decomposition of data into distributed arrays in C.

Function Documentation

PIOc_init_decomp()

int PIOc_init_decomp	(	int	iosysid,
		int	pio_type,
		int	ndims,
		const int *	gdimlen,
		int	maplen,
		const PIO_Offset *	compmap,
		int *	ioidp,
		int	rearranger,
		const PIO_Offset *	iostart,
		const PIO_Offset *	iocount
	)

Initialize the decomposition used with distributed arrays.

The decomposition describes how the data will be distributed between tasks.

Parameters

iosysid	the IO system ID.
pio_type	the basic PIO data type used.
ndims	the number of dimensions in the variable, not including the unlimited dimension.
gdimlen	an array length ndims with the sizes of the global dimensions.
maplen	the local length of the compmap array.
compmap	a 0 based array of offsets into the array record on file. A -1 in this array indicates a value which should not be transfered.
ioidp	pointer that will get the io description ID.
rearranger	the rearranger to be used for this decomp or 0 to use the default. Valid rearrangers are PIO_REARR_BOX and PIO_REARR_SUBSET.
iostart	An array of start values for block cyclic decompositions. If NULL ???
iocount	An array of count values for block cyclic decompositions. If NULL ???

Returns

0 on success, error code otherwise

Author

Jim Edwards, Ed Hartnett

PIOc_InitDecomp()

int PIOc_InitDecomp	(	int	iosysid,
		int	pio_type,
		int	ndims,
		const int *	gdimlen,
		int	maplen,
		const PIO_Offset *	compmap,
		int *	ioidp,
		const int *	rearranger,
		const PIO_Offset *	iostart,
		const PIO_Offset *	iocount
	)

Initialize the decomposition used with distributed arrays.

The decomposition describes how the data will be distributed between tasks.

Internally, this function will:

• Allocate and initialize an iodesc struct for this decomposition. (This also allocates an io_region struct for the first region.)
• (Box rearranger only) If iostart or iocount are NULL, call CalcStartandCount() to determine starts/counts. Then call compute_maxIObuffersize() to compute the max IO buffer size needed.
• Create the rearranger.
• Assign an ioid and add this decomposition to the list of open decompositions.

Parameters

iosysid	the IO system ID.
pio_type	the basic PIO data type used.
ndims	the number of dimensions in the variable, not including the unlimited dimension.
gdimlen	an array length ndims with the sizes of the global dimensions.
maplen	the local length of the compmap array.
compmap	a 1 based array of offsets into the array record on file. A 0 in this array indicates a value which should not be transfered.
ioidp	pointer that will get the io description ID. Ignored if NULL.
rearranger	pointer to the rearranger to be used for this decomp or NULL to use the default.
iostart	An array of start values for block cyclic decompositions for the SUBSET rearranger. Ignored if block rearranger is used. If NULL and SUBSET rearranger is used, the iostarts are generated.
iocount	An array of count values for block cyclic decompositions for the SUBSET rearranger. Ignored if block rearranger is used. If NULL and SUBSET rearranger is used, the iostarts are generated.

Returns

0 on success, error code otherwise

Author

Jim Edwards, Ed Hartnett

PIOc_InitDecomp_bc()

int PIOc_InitDecomp_bc	(	int	iosysid,
		int	pio_type,
		int	ndims,
		const int *	gdimlen,
		const long int *	start,
		const long int *	count,
		int *	ioidp
	)

This is a simplified initdecomp which can be used if the memory order of the data can be expressed in terms of start and count on the file.

In this case we compute the compdof.

Parameters

iosysid	the IO system ID
pio_type
ndims	the number of dimensions
gdimlen	an array length ndims with the sizes of the global dimensions.
start	start array
count	count array
ioidp	pointer that gets the IO ID.

Returns

0 for success, error code otherwise

Author

Jim Edwards