Profiling, Performance, and Perfection 
<p>[This article originally appeared as a tutorial in the
ACM SIGAPL APL89 Conference Proceedings.]

<P>A PROFILE is ``a set of data often in graphic form portraying 
the significant features of something"}.
 Profiles can help us to quickly understand a person or entity better.
 In the development of 
computer-based applications, profiles are invaluable. They help us to 
understand the application -- how it works, how well it works, whether it in 
fact works as we think it does,
 and whether it is still working the same way it did last month.

<P>For our purposes, profiling is the analysis of a running computer program
 in order
to determine its actual, rather than predicted, behavior. Profiling may be 
performed manually, or automatically, with the aid of hardware or 
software. The data collected by a profiling activity depends 
on the type of analysis to be performed, but typically will 
allow determination of instruction mix, storage reference 
patterns, 
and instruction reference patterns. 

<P>This tutorial presents several tools for profiling 
of APL and non-APL languages and discusses their utility in improving the 
quality and performance of applications. As well, several case 
studies are presented, which are 
intended to provide some insight into how profiling tools 
might profitably be used in your own work.


<p>The profiling article is available in <A HREF="apl89ppp.pdf">PDF (102k)</A> 
format and in  <A HREF="apl89ppp.ps">PostScript (169k)</A> format.