1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
|
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<!--Converted with LaTeX2HTML 96.1-h (September 30, 1996) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds -->
<HTML>
<HEAD>
<TITLE>Achieving High Performance on a Distributed Memory
Computer</TITLE>
<META NAME="description" CONTENT="Achieving High Performance on a Distributed Memory
Computer">
<META NAME="keywords" CONTENT="slug">
<META NAME="resource-type" CONTENT="document">
<META NAME="distribution" CONTENT="global">
<LINK REL=STYLESHEET HREF="slug.css">
</HEAD>
<BODY LANG="EN" >
<A NAME="tex2html3533" HREF="node107.html"><IMG WIDTH=37 HEIGHT=24 ALIGN=BOTTOM ALT="next" SRC="http://www.netlib.org/utk/icons/next_motif.gif"></A> <A NAME="tex2html3531" HREF="node105.html"><IMG WIDTH=26 HEIGHT=24 ALIGN=BOTTOM ALT="up" SRC="http://www.netlib.org/utk/icons/up_motif.gif"></A> <A NAME="tex2html3525" HREF="node105.html"><IMG WIDTH=63 HEIGHT=24 ALIGN=BOTTOM ALT="previous" SRC="http://www.netlib.org/utk/icons/previous_motif.gif"></A> <A NAME="tex2html3535" HREF="node1.html"><IMG WIDTH=65 HEIGHT=24 ALIGN=BOTTOM ALT="contents" SRC="http://www.netlib.org/utk/icons/contents_motif.gif"></A> <A NAME="tex2html3536" HREF="node190.html"><IMG WIDTH=43 HEIGHT=24 ALIGN=BOTTOM ALT="index" SRC="http://www.netlib.org/utk/icons/index_motif.gif"></A> <BR>
<B> Next:</B> <A NAME="tex2html3534" HREF="node107.html">Achieving High Performance on </A>
<B>Up:</B> <A NAME="tex2html3532" HREF="node105.html">Achieving High Performance with </A>
<B> Previous:</B> <A NAME="tex2html3526" HREF="node105.html">Achieving High Performance with </A>
<BR> <P>
<H2><A NAME="SECTION04511000000000000000">Achieving High Performance on a Distributed Memory
Computer</A></H2>
<A NAME="distmemcomp"> </A><A NAME="3551"> </A>
<A NAME="3552"> </A><A NAME="3553"> </A><A NAME="3554"> </A>
<P>
Assuming that the ScaLAPACK installation was done correctly, the users need
only make sure that they are using an appropriate number of processors
and that their matrices are efficiently distributed. Here is a
checklist to get started.
<P>
<UL>
<LI>Use the right number of processors.
<UL>
<LI>Rule of thumb: <IMG WIDTH=159 HEIGHT=27 ALIGN=MIDDLE ALT="tex2html_wrap_inline16164" SRC="img362.gif"> for an <IMG WIDTH=55 HEIGHT=22 ALIGN=MIDDLE ALT="tex2html_wrap_inline15127" SRC="img315.gif"> matrix.
This provides a local matrix of size approximately 1000 by 1000.<A NAME="3558"> </A>
<LI> Do not try to solve a small problem on too many processors.
<LI>Do not exceed physical memory.
</UL>
<LI>Use an efficient data distribution.
<UL>
<LI> Block size<A NAME="tex2html906" HREF="footnode.html#3563"><IMG ALIGN=BOTTOM ALT="gif" SRC="http://www.netlib.org/utk/icons/foot_motif.gif"></A> (i.e., <I>MB</I>,<I>NB</I>) = 64.<A NAME="3564"> </A>
<LI> Square processor grid, <IMG WIDTH=59 HEIGHT=25 ALIGN=MIDDLE ALT="tex2html_wrap_inline16172" SRC="img363.gif">.<A NAME="3567"> </A>
</UL>
<LI>Use efficient machine-specific BLAS (not the Fortran 77 reference
implementation BLAS) and BLACS (nondebug, <I>BLACSDBGLVL</I>=0 in
<TT>Bmake.inc</TT>)
</UL>
<P>
If the performance is still below that expected, see
section <A HREF="node120.html#secperfeval">5.3</A>. For guidelines on tuning for higher performance,
see section <A HREF="node127.html#secperfimprovement">5.4</A>.
<P>
<BR> <HR>
<P><ADDRESS>
<I>Susan Blackford <BR>
Tue May 13 09:21:01 EDT 1997</I>
</ADDRESS>
</BODY>
</HTML>
|
