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From: jrv@siemens.UUCP
Newsgroups: net.micro.pc
Subject: Re: CTL-T on PC...
Message-ID: <23900026@siemens.UUCP>
Date: Fri, 20-Jun-86 09:59:00 EDT
Article-I.D.: siemens.23900026
Posted: Fri Jun 20 09:59:00 1986
Date-Received: Sun, 22-Jun-86 04:18:47 EDT
References: <5444@think.UUCP>
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Nf-ID: #R:think:-544400:siemens:23900026:000:1400
Nf-From: siemens!jrv    Jun 20 09:59:00 1986




Maybe what the poster is asking for is an execution profiler. After hitting
the RETURN key and watching and waiting he might wonder what the poor
compaq is doing *while executing* his program. My use of Cntl-T mostly
occurs as a futile answer for my question "Why is this program taking so
long?" Cntl-T "Ah, the system is attempting to run well beyond its
capabilities. Where did I put that magazine?"

Tuning your program is something which few people seem to do. A few months
ago someone posted a request for techniques used for tuning programs.
I was the only response he got and I was asking for him to forward the
answers he got. For a while I was associated with a program widely known
as being a DOG. It was 200K of FORTRAN code and 350K of data. After a
little work with a logic analyzer to profile the execution of the program
we found that 25% of the time was spent in 5 lines of FORTRAN. By reworking
the algorithm used and putting in some judious assembly language the program
was speed up by 20%. Not an order of magnitude but still helpfull.

There are several software profilers available to run on IBM and compatible
computers. All of them take their toll on execution speed. A hardware
assisted approach when allow full speed execution but at much higher cost.


Jim Vallino
Siemens Research and Technology Lab.
Princeton, NJ
{allegra,ihnp4,seismo,philabs}!princeton!siemens!jrv