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<TITLE>3 A Quantitative Basis for Design</TITLE>
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<B> Next:</B> <A NAME=tex2html2162 HREF="node27.html" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node27.html">3.1 Defining Performance</A>
<B>Up:</B> <A NAME=tex2html2160 HREF="node4.html" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node4.html">Part I: Concepts</A>
<B> Previous:</B> <A NAME=tex2html2154 HREF="node25.html" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node25.html"> Chapter Notes</A>
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<H1><A NAME=SECTION02400000000000000000>3 A Quantitative Basis for Design</A></H1>
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<A NAME=chapperf> </A>
<P>
In parallel programming, as in other engineering disciplines, the goal
of the design process is not to optimize a single metric such as
speed. Rather, a good design must optimize a problem-specific
function of execution time, memory requirements, implementation costs,
maintenance costs, and so on. Such design optimization involves
tradeoffs between simplicity, performance, portability, and other
factors.
<P>
Making informed design decisions about alternatives requires an
understanding of their costs. In this chapter, we show how this
understanding can be developed and formalized in mathematical <em>
performance models</em>. These models can be used to compare the
efficiency of different algorithms, to evaluate scalability, and to
identify bottlenecks and other inefficiencies, all <em> before
</em> we
invest substantial effort in an implementation. Performance models
can also be used to guide implementation efforts by showing where
optimization is needed.
<P>
After studying this chapter, you should know how to develop
performance models for parallel algorithms and be able to use these
models to evaluate scalability and to choose between alternative
algorithms. You also should know how to obtain reliable empirical
data and how to use this data to validate models and implementations.
Further, you should understand how network topology can affect
communication performance, and you should know how to account for
these effects in your models. Finally, you should be able to
recognize and account for factors other than performance, factors such
as implementation costs, that influence design choices.
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<LI> <A NAME=tex2html2165 HREF="node27.html#SECTION02410000000000000000" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node27.html#SECTION02410000000000000000">3.1 Defining Performance</A>
<LI> <A NAME=tex2html2166 HREF="node28.html#SECTION02420000000000000000" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node28.html#SECTION02420000000000000000">3.2 Approaches to Performance Modeling</A>
<LI> <A NAME=tex2html2167 HREF="node29.html#SECTION02430000000000000000" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node29.html#SECTION02430000000000000000">3.3 Developing Models</A>
<LI> <A NAME=tex2html2168 HREF="node30.html#SECTION02440000000000000000" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node30.html#SECTION02440000000000000000">3.4 Scalability Analysis</A>
<LI> <A NAME=tex2html2169 HREF="node31.html#SECTION02450000000000000000" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node31.html#SECTION02450000000000000000">3.5 Experimental Studies</A>
<LI> <A NAME=tex2html2170 HREF="node32.html#SECTION02460000000000000000" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node32.html#SECTION02460000000000000000">3.6 Evaluating Implementations</A>
<LI> <A NAME=tex2html2171 HREF="node33.html#SECTION02470000000000000000" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node33.html#SECTION02470000000000000000">3.7 A Refined Communication Cost Model</A>
<LI> <A NAME=tex2html2172 HREF="node34.html#SECTION02480000000000000000" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node34.html#SECTION02480000000000000000">3.8 Input/Output</A>
<LI> <A NAME=tex2html2173 HREF="msgs0.htm#24" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/tppmsgs/msgs0.htm#24">3.9 Case Study: Shortest-Path Algorithms</A>
<LI> <A NAME=tex2html2174 HREF="node36.html#SECTION024100000000000000000" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node36.html#SECTION024100000000000000000">3.10 Summary</A>
<LI> <A NAME=tex2html2175 HREF="node37.html#SECTION024110000000000000000" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node37.html#SECTION024110000000000000000"> Exercises</A>
<LI> <A NAME=tex2html2176 HREF="node38.html#SECTION024120000000000000000" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node38.html#SECTION024120000000000000000"> Chapter Notes</A>
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<BR> <HR><a href="msgs0.htm#2" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/tppmsgs/msgs0.htm#2"><img ALIGN=MIDDLE src="asm_color_tiny.gif" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/asm_color_tiny.gif" alt="[DBPP]"></a> <A NAME=tex2html2153 HREF="node25.html" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node25.html"><IMG ALIGN=MIDDLE ALT="previous" SRC="previous_motif.gif" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/previous_motif.gif"></A> <A NAME=tex2html2161 HREF="node27.html" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node27.html"><IMG ALIGN=MIDDLE ALT="next" SRC="next_motif.gif" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/next_motif.gif"></A> <A NAME=tex2html2159 HREF="node4.html" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node4.html"><IMG ALIGN=MIDDLE ALT="up" SRC="up_motif.gif" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/up_motif.gif"></A> <A NAME=tex2html2163 HREF="node1.html" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node1.html"><IMG ALIGN=MIDDLE ALT="contents" SRC="contents_motif.gif" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/contents_motif.gif"></A> <A NAME=tex2html2164 HREF="node133.html" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node133.html"><IMG ALIGN=MIDDLE ALT="index" SRC="index_motif.gif" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/index_motif.gif"></A> <a href="msgs0.htm#3" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/tppmsgs/msgs0.htm#3"><img ALIGN=MIDDLE src="search_motif.gif" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/search_motif.gif" alt="[Search]"></a> <BR>
<B> Next:</B> <A NAME=tex2html2162 HREF="node27.html" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node27.html">3.1 Defining Performance</A>
<B>Up:</B> <A NAME=tex2html2160 HREF="node4.html" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node4.html">Part I: Concepts</A>
<B> Previous:</B> <A NAME=tex2html2154 HREF="node25.html" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/node25.html"> Chapter Notes</A>
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<I>© Copyright 1995 by <A href="msgs0.htm#6" tppabs="http://www.dit.hcmut.edu.vn/books/system/par_anl/tppmsgs/msgs0.htm#6">Ian Foster</a></I>
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