You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
250 lines
7.7 KiB
HTML
250 lines
7.7 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
|
|
|
|
<!--Converted with LaTeX2HTML 2008 (1.71)
|
|
original version by: Nikos Drakos, CBLU, University of Leeds
|
|
* revised and updated by: Marcus Hennecke, Ross Moore, Herb Swan
|
|
* with significant contributions from:
|
|
Jens Lippmann, Marek Rouchal, Martin Wilck and others -->
|
|
<HTML>
|
|
<HEAD>
|
|
<TITLE>Descriptor data structure</TITLE>
|
|
<META NAME="description" CONTENT="Descriptor data structure">
|
|
<META NAME="keywords" CONTENT="userhtml">
|
|
<META NAME="resource-type" CONTENT="document">
|
|
<META NAME="distribution" CONTENT="global">
|
|
|
|
<META NAME="Generator" CONTENT="LaTeX2HTML v2008">
|
|
<META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css">
|
|
|
|
<LINK REL="STYLESHEET" HREF="userhtml.css">
|
|
|
|
<LINK REL="next" HREF="node11.html">
|
|
<LINK REL="previous" HREF="node8.html">
|
|
<LINK REL="up" HREF="node8.html">
|
|
<LINK REL="next" HREF="node10.html">
|
|
</HEAD>
|
|
|
|
<BODY >
|
|
<!--Navigation Panel-->
|
|
<A NAME="tex2html288"
|
|
HREF="node10.html">
|
|
<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.png"></A>
|
|
<A NAME="tex2html284"
|
|
HREF="node8.html">
|
|
<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.png"></A>
|
|
<A NAME="tex2html278"
|
|
HREF="node8.html">
|
|
<IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.png"></A>
|
|
<A NAME="tex2html286"
|
|
HREF="node1.html">
|
|
<IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.png"></A>
|
|
<BR>
|
|
<B> Next:</B> <A NAME="tex2html289"
|
|
HREF="node10.html">Named Constants</A>
|
|
<B> Up:</B> <A NAME="tex2html285"
|
|
HREF="node8.html">Data Structures</A>
|
|
<B> Previous:</B> <A NAME="tex2html279"
|
|
HREF="node8.html">Data Structures</A>
|
|
<B> <A NAME="tex2html287"
|
|
HREF="node1.html">Contents</A></B>
|
|
<BR>
|
|
<BR>
|
|
<!--End of Navigation Panel-->
|
|
|
|
<H2><A NAME="SECTION00041000000000000000"></A>
|
|
<A NAME="sec:desc"></A>
|
|
<BR>
|
|
Descriptor data structure
|
|
</H2>
|
|
All the general matrix informations and elements to be
|
|
exchanged among processes are stored within a data structure of the
|
|
type descdata<TT>psb_desc_type</TT>.
|
|
Every structure of this type is associated to a sparse matrix, it
|
|
contains data about general matrix informations and elements to be
|
|
exchanged among processes.
|
|
|
|
<P>
|
|
It is not necessary for the user to know the internal structure of
|
|
<code>psb_desc_type</code>, it is set in a transparent mode by the tools
|
|
routines of Sec. <A HREF="node45.html#sec:toolsrout">6</A>, and its fields may be accessed
|
|
if necessary via the routines of sec. <A HREF="node16.html#sec:dataquery">3.5</A>;
|
|
nevertheless we include a description for the curious
|
|
reader:
|
|
<DL>
|
|
<DT><STRONG><B>matrix_data</B></STRONG></DT>
|
|
<DD>includes general information about matrix and
|
|
process grid, such as the communication context, the size of the
|
|
global matrix, the size of the portion of matrix stored on the current
|
|
process, and so on.
|
|
Specified as: an allocatable integer array of dimension <code>psb_mdata_size_</code>.
|
|
</DD>
|
|
<DT><STRONG><B>halo_index</B></STRONG></DT>
|
|
<DD>A list of the halo and boundary elements for
|
|
the current process to be exchanged with other processes; for each
|
|
processes with which it is necessary to communicate:
|
|
|
|
<OL>
|
|
<LI>Process identifier;
|
|
</LI>
|
|
<LI>Number of points to be received;
|
|
</LI>
|
|
<LI>Indices of points to be received;
|
|
</LI>
|
|
<LI>Number of points to be sent;
|
|
</LI>
|
|
<LI>Indices of points to be sent;
|
|
</LI>
|
|
</OL>
|
|
The list may contain an arbitrary number of groups; its end is marked
|
|
by a -1.
|
|
<BR>
|
|
Specified as: an allocatable integer array of rank one.
|
|
</DD>
|
|
<DT><STRONG><B>ext_index</B></STRONG></DT>
|
|
<DD>A list of element indices to be exchanged to
|
|
implement the mapping between a base descriptor and a descriptor
|
|
with overlap.
|
|
</DD>
|
|
<DT><STRONG><B>ovrlap_index</B></STRONG></DT>
|
|
<DD>A list of the overlap elements for the
|
|
current process, organized in groups like the previous vector:
|
|
|
|
<OL>
|
|
<LI>Process identifier;
|
|
</LI>
|
|
<LI>Number of points to be received;
|
|
</LI>
|
|
<LI>Indices of points to be received;
|
|
</LI>
|
|
<LI>Number of points to be sent;
|
|
</LI>
|
|
<LI>Indices of points to be sent;
|
|
</LI>
|
|
</OL>
|
|
The list may contain an arbitrary number of groups; its end is marked
|
|
by a -1.
|
|
<BR>
|
|
Specified as: an allocatable integer array of rank one.
|
|
</DD>
|
|
<DT><STRONG><B>ovr_mst_idx</B></STRONG></DT>
|
|
<DD>A list to retrieve the value of each
|
|
overlap element from the respective master process.
|
|
<BR>
|
|
Specified as: an allocatable integer array of rank one.
|
|
</DD>
|
|
<DT><STRONG><B>ovrlap_elem</B></STRONG></DT>
|
|
<DD>For all overlap points belonging to th
|
|
ecurrent process:
|
|
|
|
<OL>
|
|
<LI>Overlap point index;
|
|
</LI>
|
|
<LI>Number of processes sharing that overlap points;
|
|
</LI>
|
|
<LI>Index of a ``master'' process:
|
|
</LI>
|
|
</OL>
|
|
Specified as: an allocatable integer array of rank two.
|
|
</DD>
|
|
<DT><STRONG><B>loc_to_glob</B></STRONG></DT>
|
|
<DD>each element <IMG
|
|
WIDTH="9" HEIGHT="17" ALIGN="BOTTOM" BORDER="0"
|
|
SRC="img4.png"
|
|
ALT="$i$"> of this array contains
|
|
global identifier of the local variable <IMG
|
|
WIDTH="9" HEIGHT="17" ALIGN="BOTTOM" BORDER="0"
|
|
SRC="img4.png"
|
|
ALT="$i$">.
|
|
<BR>
|
|
Specified as: an allocatable integer array of rank one.
|
|
</DD>
|
|
<DT><STRONG><B>glob_to_loc, glb_lc, hashv</B></STRONG></DT>
|
|
<DD>Contain a mapping from
|
|
global to local indices.
|
|
</DD>
|
|
</DL>
|
|
The Fortran 95 definition for <code>psb_desc_type</code> structures is
|
|
as follows:
|
|
|
|
<DIV ALIGN="CENTER"><A NAME="fig:desctype"></A><A NAME="668"></A>
|
|
<TABLE>
|
|
<CAPTION ALIGN="BOTTOM"><STRONG>Figure 3:</STRONG>
|
|
The PSBLAS defined data type that
|
|
contains the communication descriptor.</CAPTION>
|
|
<TR><TD>
|
|
<BR>
|
|
|
|
<DIV ALIGN="CENTER">
|
|
<!-- MATH
|
|
$\fbox{\TheSbox}$
|
|
-->
|
|
<IMG
|
|
WIDTH="535" HEIGHT="218" ALIGN="MIDDLE" BORDER="0"
|
|
SRC="img20.png"
|
|
ALT="\fbox{\TheSbox}">
|
|
</DIV></TD></TR>
|
|
</TABLE>
|
|
</DIV>
|
|
|
|
<P>
|
|
A communication descriptor associated with a sparse matrix has a
|
|
state, which can take the following values:
|
|
<DL>
|
|
<DT><STRONG>Build:</STRONG></DT>
|
|
<DD>State entered after the first allocation, and before the
|
|
first assembly; in this state it is possible to add communication
|
|
requirements among different processes.
|
|
</DD>
|
|
<DT><STRONG>Assembled:</STRONG></DT>
|
|
<DD>State entered after the assembly; computations using
|
|
the associated sparse matrix, such as matrix-vector products, are
|
|
only possible in this state.
|
|
</DD>
|
|
</DL>
|
|
The global to local index mapping may be stored in two different
|
|
formats: the first is simpler but more expensive, as it requires on
|
|
each process an amount of memory proportional to the global size of
|
|
the index space; the second is more complex, but only requires memory
|
|
proportional to the local index space size. The choice is made at the
|
|
time of the initialization according to a threshold; this threshold
|
|
may be queried and set using the functions in
|
|
sec. <A HREF="node16.html#sec:dataquery">3.5</A>.
|
|
|
|
<P>
|
|
<BR><HR>
|
|
<!--Table of Child-Links-->
|
|
<A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></A>
|
|
|
|
<UL>
|
|
<LI><A NAME="tex2html290"
|
|
HREF="node10.html">Named Constants</A>
|
|
</UL>
|
|
<!--End of Table of Child-Links-->
|
|
<HR>
|
|
<!--Navigation Panel-->
|
|
<A NAME="tex2html288"
|
|
HREF="node10.html">
|
|
<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.png"></A>
|
|
<A NAME="tex2html284"
|
|
HREF="node8.html">
|
|
<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.png"></A>
|
|
<A NAME="tex2html278"
|
|
HREF="node8.html">
|
|
<IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.png"></A>
|
|
<A NAME="tex2html286"
|
|
HREF="node1.html">
|
|
<IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.png"></A>
|
|
<BR>
|
|
<B> Next:</B> <A NAME="tex2html289"
|
|
HREF="node10.html">Named Constants</A>
|
|
<B> Up:</B> <A NAME="tex2html285"
|
|
HREF="node8.html">Data Structures</A>
|
|
<B> Previous:</B> <A NAME="tex2html279"
|
|
HREF="node8.html">Data Structures</A>
|
|
<B> <A NAME="tex2html287"
|
|
HREF="node1.html">Contents</A></B>
|
|
<!--End of Navigation Panel-->
|
|
|
|
</BODY>
|
|
</HTML>
|