diff options
| -rw-r--r-- | doc/html/TechNotes/VFL.html | 87 |
1 files changed, 74 insertions, 13 deletions
diff --git a/doc/html/TechNotes/VFL.html b/doc/html/TechNotes/VFL.html index 5660b61..5674cdb 100644 --- a/doc/html/TechNotes/VFL.html +++ b/doc/html/TechNotes/VFL.html @@ -44,10 +44,11 @@ <LI><A NAME="TOC20" HREF="VFL.html#SEC20">Contiguous I/O Functions</A> <LI><A NAME="TOC21" HREF="VFL.html#SEC21">Flushing Cached Data</A> </UL> -<LI><A NAME="TOC22" HREF="VFL.html#SEC22">Registration of a Driver</A> -<LI><A NAME="TOC23" HREF="VFL.html#SEC23">Querying Driver Information</A> +<LI><A NAME="TOC22" HREF="VFL.html#SEC22">Optimization Functions</A> +<LI><A NAME="TOC23" HREF="VFL.html#SEC23">Registration of a Driver</A> +<LI><A NAME="TOC24" HREF="VFL.html#SEC24">Querying Driver Information</A> </UL> -<LI><A NAME="TOC24" HREF="VFL.html#SEC24">Miscellaneous</A> +<LI><A NAME="TOC25" HREF="VFL.html#SEC25">Miscellaneous</A> </UL> <P><HR><P> @@ -1058,9 +1059,9 @@ file and vice versa. </P> <P> <DL> -<DT><U>Function:</U> static herr_t <B>read</B> <I>(H5FD_t *<VAR>file</VAR>, hid_t <VAR>dxpl</VAR>, haddr_t <VAR>addr</VAR>, hsize_t <VAR>size</VAR>, void *<VAR>buf</VAR>)</I> +<DT><U>Function:</U> static herr_t <B>read</B> <I>(H5FD_t *<VAR>file</VAR>, H5FD_mem_t <VAR>type</VAR>, hid_t <VAR>dxpl</VAR>, haddr_t <VAR>addr</VAR>, hsize_t <VAR>size</VAR>, void *<VAR>buf</VAR>)</I> <DD><A NAME="IDX10"></A> -<DT><U>Function:</U> static herr_t <B>write</B> <I>(H5FD_t *<VAR>file</VAR>, hid_t <VAR>dxpl</VAR>, haddr_t <VAR>addr</VAR>, hsize_t <VAR>size</VAR>, const void *<VAR>buf</VAR>)</I> +<DT><U>Function:</U> static herr_t <B>write</B> <I>(H5FD_t *<VAR>file</VAR>, H5FD_mem_t <VAR>type</VAR>, hid_t <VAR>dxpl</VAR>, haddr_t <VAR>addr</VAR>, hsize_t <VAR>size</VAR>, const void *<VAR>buf</VAR>)</I> <DD><A NAME="IDX11"></A> </P> @@ -1071,7 +1072,9 @@ supplied by the caller. The <CODE>write</CODE> function transfers data in the opposite direction. Both functions take a data transfer property list <VAR>dxpl</VAR> which indicates the fine points of how the data is to be transferred and which comes directly from the <CODE>H5Dread</CODE> or -<CODE>H5Dwrite</CODE> function. +<CODE>H5Dwrite</CODE> function. Both functions receive <VAR>type</VAR> of +data being written, which may allow a driver to tune it's behavior for +different kinds of data. </DL> </P> @@ -1092,8 +1095,8 @@ system calls which were interrupted. <PRE> static herr_t -H5FD_sec2_read(H5FD_t *_file, hid_t dxpl_id/*unused*/, haddr_t addr, - hsize_t size, void *buf/*out*/) +H5FD_sec2_read(H5FD_t *_file, H5FD_mem_t type/*unused*/, hid_t dxpl_id/*unused*/, + haddr_t addr, hsize_t size, void *buf/*out*/) { H5FD_sec2_t *file = (H5FD_sec2_t*)_file; ssize_t nbytes; @@ -1203,7 +1206,57 @@ H5FD_sec2_flush(H5FD_t *_file) -<H2><A NAME="SEC22" HREF="VFL.html#TOC22">Registration of a Driver</A></H2> +<H2><A NAME="SEC22" HREF="VFL.html#TOC22">Optimization Functions</A></H2> + +<P> +The library is capable of performing several generic optimizations on I/O, but +these types of optimizations may not be appropriate for a given VFL driver. +</P> + +<P> +Each driver may provide a query function to allow the library to query whether +to enable these optimizations. If a driver lacks a query function, the library +will disable all types of optimizations which can be queried. +</P> + +<P> +<DL> +<DT><U>Function:</U> static herr_t <B>query</B> <I>(const H5FD_t *<VAR>file</VAR>, unsigned long *<VAR>flags</VAR>)</I> +<DD><A NAME="IDX17"></A> +</P> +<P> +This function is called by the library to query which optimizations to enable +for I/O to this driver. These are the flags which are currently defined: + +<UL> +<DL> +<DT>H5FD_FEAT_AGGREGATE_METADATA (0x00000001) +<DD>Defining the H5FD_FEAT_AGGREGATE_METADATA for a VFL driver means that +the library will attempt to allocate a larger block for metadata and +then sub-allocate each metadata request from that larger block. +<DT>H5FD_FEAT_ACCUMULATE_METADATA (0x00000002) +<DD>Defining the H5FD_FEAT_ACCUMULATE_METADATA for a VFL driver means that +the library will attempt to cache metadata as it is written to the file +and build up a larger block of metadata to eventually pass to the VFL +'write' routine. +<DT>H5FD_FEAT_DATA_SIEVE (0x00000004) +<DD>Defining the H5FD_FEAT_DATA_SIEVE for a VFL driver means that +the library will attempt to cache raw data as it is read from/written to +a file in a "data sieve" buffer. See Rajeev Thakur's papers: + <UL> + <DL> + <DT>http://www.mcs.anl.gov/~thakur/papers/romio-coll.ps.gz + <DT>http://www.mcs.anl.gov/~thakur/papers/mpio-high-perf.ps.gz + </DL> + </UL> +</DL> +</UL> +</P> + +</DL> +</P> + +<H2><A NAME="SEC23" HREF="VFL.html#TOC23">Registration of a Driver</A></H2> <P> Before a driver can be used the HDF5 library needs to be told of its @@ -1275,6 +1328,10 @@ The function which ends access to a file. An optional function to determine whether two open files have the same key. If this function is not present then the library assumes that two files will never be the same. +<DT><CODE>int (*query)(const H5FD_t *f, unsigned long *flags)</CODE> +<DD> +An optional function to determine which library optimizations a driver can +support. <DT><CODE>haddr_t (*alloc)(H5FD_t *file, H5FD_mem_t type, hsize_t size)</CODE> <DD> An optional function to allocate space in the file. @@ -1290,10 +1347,10 @@ A function to set the end of address space. <DT><CODE>haddr_t (*get_eof)(H5FD_t *file)</CODE> <DD> A function to return the current end-of-file marker value. -<DT><CODE>herr_t (*read)(H5FD_t *file, hid_t dxpl, haddr_t addr, hsize_t size, void *buffer)</CODE> +<DT><CODE>herr_t (*read)(H5FD_t *file, H5FD_mem_t type, hid_t dxpl, haddr_t addr, hsize_t size, void *buffer)</CODE> <DD> A function to read data from a file. -<DT><CODE>herr_t (*write)(H5FD_t *file, hid_t dxpl, haddr_t addr, hsize_t size, const void *buffer)</CODE> +<DT><CODE>herr_t (*write)(H5FD_t *file, H5FD_mem_t type, hid_t dxpl, haddr_t addr, hsize_t size, const void *buffer)</CODE> <DD> A function to write data to a file. <DT><CODE>herr_t (*flush)(H5FD_t *file)</CODE> @@ -1326,6 +1383,7 @@ static const H5FD_class_t H5FD_sec2_g = { H5FD_sec2_open, /*open */ H5FD_sec2_close, /*close */ H5FD_sec2_cmp, /*cmp */ + H5FD_sec2_query, /*query */ NULL, /*alloc */ NULL, /*free */ H5FD_sec2_get_eoa, /*get_eoa */ @@ -1368,7 +1426,7 @@ already use that driver. -<H2><A NAME="SEC23" HREF="VFL.html#TOC23">Querying Driver Information</A></H2> +<H2><A NAME="SEC24" HREF="VFL.html#TOC24">Querying Driver Information</A></H2> <P> <DL> @@ -1390,7 +1448,7 @@ driver-specific data transfer information instead. </P> -<H1><A NAME="SEC24" HREF="VFL.html#TOC24">Miscellaneous</A></H1> +<H1><A NAME="SEC25" HREF="VFL.html#TOC25">Miscellaneous</A></H1> <P> The various private <CODE>H5F_low_*</CODE> functions will be replaced by public @@ -1478,5 +1536,8 @@ in the missing parts of the mapping. This document was generated on 18 November 1999 using the <A HREF="http://wwwcn.cern.ch/dci/texi2html/">texi2html</A> translator version 1.51.</P> +<P> +Updated on 10/24/00 by hand, Quincey Koziol +</P> </BODY> </HTML> |