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From: kempf@hplabsc.UUCP
Newsgroups: comp.lang.lisp
Subject: Profiling Common Lisp
Message-ID: <1310@hplabsc.UUCP>
Date: Tue, 17-Feb-87 12:23:21 EST
Article-I.D.: hplabsc.1310
Posted: Tue Feb 17 12:23:21 1987
Date-Received: Wed, 18-Feb-87 06:08:03 EST
Organization: Hewlett-Packard Laboratories
Lines: 18

We use a 10 microsecond clock to profile our Common Lisp and we
can often shave a good deal of time off applications by identifying
functions which are slow or getting called excessively. For instance,
I was recently able to shave 10-7x off an application by using
our profiling tools. Another useful tool is a "cons-meter", which
allows the developer to identify where excessive consing is occuring.
Profiling is time consuming, however, the motivation to do it is
stronger in Lisp than in C, since applications can run unacceptably
slow if the developer doesn't know where the time is going. 
While some people might take this as an argument to simply use C,
there are some things which are difficult to do in C. Embedded languages
are relatively easy in Lisp, much more difficult in C, due to the
lack of the ability to dynamically modify the compiler.

I was interested to see that a CL application ran only 2x slower than
the equivalent C++ application. 

		Jim Kempf	kempf@hplabs.hp.com