H5Pget_mpio_actual_chunk_opt_mode
(
hid_t dxpl_id
,
H5D_mpio_actual_chunk_opt_mode_t *
actual_chunk_opt_mode
)
H5Pset_dxpl_mpio
. The operation can be optimized in
several different ways, some of which also can be requested by the
user. However, HDF5 may not be able to satisfy requests for
specific optimizations and may choose a different
optimization scheme. This property allows the user to track which
optimization was actually used. Used in conjunction with
H5Pget_mpio_actual_io_mode
, this property allows the
user to determine exactly what HDF5 did when attempting collective
chunked I/O.
H5Pget_mpio_actual_chunk_opt_mode
retrieves the type of chunk optimization performed when collective
I/O was requested. This property is set before I/O takes place, and
will be set even if I/O fails.
Valid values returned in actual_chunk_opt_mode
:
H5D_MPIO_NO_CHUNK_OPTIMIZATION
|
No chunk optimization was performed. Either no collective I/O
was attempted or the dataset wasn't chunked.
(Default) | ||
H5D_MPIO_MULTI_CHUNK
|
Each chunk was individually assigned collective or independent I/O
based on what fraction of processes access the chunk. If the fraction
is greater than the multi chunk ratio threshold, collective I/O is
performed on that chunk. The multi chunk ratio threshold can be set
using H5Pset_dxpl_mpio_chunk_opt_ratio . The default
value is 60%.
| ||
H5D_MPIO_MULTI_CHUNK_NO_OPT
|
Each chunk is assigned collective or independent I/O based on how many chunks were accessed before it. Collective I/O is performed on the the first chunk in each selection, then the second, and so on until one process finishes, then the remaining processes perform independent I/O on the rest of their selections. | ||
H5D_MPIO_LINK_CHUNK
|
Collective I/O is performed on all chunks simultaneously. |
hid_t dxpl_id
| IN: Dataset transfer property list identifier | |
H5D_mpio_actual_chunk_opt_mode_t *
actual_chunk_opt_mode
| OUT: The type of chunk optimization performed by HDF5. |
H5Pget_mpio_no_collective_cause
| Reports whether collective I/O was performed on a particular call and, if not, the causes that broke collective I/O. |
H5Pget_mpio_actual_io_mode
| Reports type of I/O HDF5 actually performed. |
The following functions request optimizations or change values that HDF5 uses to choose an optimization scheme: H5Pset_dxpl_mpio_chunk_opt H5Pset_dxpl_mpio_chunk_opt_num H5Pset_dxpl_mpio_chunk_opt_ratio H5Pset_dxpl_mpio_collective_opt |
Release | Change |
1.8.8 | C function introduced in this release. |