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author | Dana Robinson <derobins@hdfgroup.org> | 2021-05-03 21:55:26 (GMT) |
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committer | Dana Robinson <derobins@hdfgroup.org> | 2021-05-03 21:55:26 (GMT) |
commit | 0ab5dd5e8ea2342ef039f0f79bd76e4ab187dddf (patch) | |
tree | 6900490d46d768f991e7cc91d45d4f8dc17985a4 /src/H5FDdirect.h | |
parent | fca509b7d61b9dffae85be3406ca484c1bf28242 (diff) | |
download | hdf5-0ab5dd5e8ea2342ef039f0f79bd76e4ab187dddf.zip hdf5-0ab5dd5e8ea2342ef039f0f79bd76e4ab187dddf.tar.gz hdf5-0ab5dd5e8ea2342ef039f0f79bd76e4ab187dddf.tar.bz2 |
Brings more develop code over, especially Doxygen
Diffstat (limited to 'src/H5FDdirect.h')
-rw-r--r-- | src/H5FDdirect.h | 63 |
1 files changed, 62 insertions, 1 deletions
diff --git a/src/H5FDdirect.h b/src/H5FDdirect.h index eec10de..f06de7f 100644 --- a/src/H5FDdirect.h +++ b/src/H5FDdirect.h @@ -37,8 +37,69 @@ extern "C" { #define FBSIZE_DEF 4096 #define CBSIZE_DEF 16 * 1024 * 1024 -H5_DLL hid_t H5FD_direct_init(void); +H5_DLL hid_t H5FD_direct_init(void); + +/** + * \ingroup FAPL + * + * \brief Sets up use of the direct I/O driver + * + * \fapl_id + * \param[in] alignment Required memory alignment boundary + * \param[in] block_size File system block size + * \param[in] cbuf_size Copy buffer size + * \returns \herr_t + * + * \details H5Pset_fapl_direct() sets the file access property list, \p fapl_id, + * to use the direct I/O driver, #H5FD_DIRECT. With this driver, data + * is written to or read from the file synchronously without being + * cached by the system. + * + * File systems usually require the data address in memory, the file + * address, and the size of the data to be aligned. The HDF5 library’s + * direct I/O driver is able to handle unaligned data, though that will + * consume some additional memory resources and may slow + * performance. To get better performance, use the system function \p + * posix_memalign to align the data buffer in memory and the HDF5 + * function H5Pset_alignment() to align the data in the file. Be aware, + * however, that aligned data I/O may cause the HDF5 file to be bigger + * than the actual data size would otherwise require because the + * alignment may leave some holes in the file. + * + * \p alignment specifies the required alignment boundary in memory. + * + * \p block_size specifies the file system block size. A value of 0 + * (zero) means to use HDF5 library’s default value of 4KB. + * + * \p cbuf_size specifies the copy buffer size. + * + * \since 1.8.0 + * + */ H5_DLL herr_t H5Pset_fapl_direct(hid_t fapl_id, size_t alignment, size_t block_size, size_t cbuf_size); + +/** + * \ingroup FAPL + * + * \brief Retrieves direct I/O driver settings + * + * \fapl_id + * \param[out] boundary Required memory alignment boundary + * \param[out] block_size File system block size + * \param[out] cbuf_size Copy buffer size + * \returns \herr_t + * + * \details H5Pget_fapl_direct() retrieves the required memory alignment (\p + * alignment), file system block size (\p block_size), and copy buffer + * size (\p cbuf_size) settings for the direct I/O driver, #H5FD_DIRECT, + * from the file access property list \p fapl_id. + * + * See H5Pset_fapl_direct() for discussion of these values, + * requirements, and important considerations. + * + * \since 1.8.0 + * + */ H5_DLL herr_t H5Pget_fapl_direct(hid_t fapl_id, size_t *boundary /*out*/, size_t *block_size /*out*/, size_t *cbuf_size /*out*/); |