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From: laser-lovers@uw-beaver (laser-lovers)
Newsgroups: fa.laser-lovers
Subject: Speed of TeX and Scribe
Message-ID: <801@uw-beaver>
Date: Fri, 13-Jan-84 13:42:51 EST
Article-I.D.: uw-beave.801
Posted: Fri Jan 13 13:42:51 1984
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Organization: U of Washington Computer Science
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From DRF@SU-SCORE.ARPA Fri Jan 13 10:42:45 1984
Please forward this to Laser-Lovers, if it seems reasonable.	-david

I know all benchmarks are wrong, but just to get a feel for things, I
tried the following experiment: Create a file with 100 paragraphs,
each with ten sentences that say "This is lots and lots of text."  Run
it on an unladen 20 with Scribe and then TeX (add "\bye" at the end
for TeX).  The results I get (using Control-T) are that TeX takes an
average of 12.5 CPU seconds, while Scribe takes an average of 11.5 CPU
seconds.  Individual measurements varied almost up to 1 second.  This
seems to indicate that TeX and Scribe run at about the same speed.  In
Scribe's favor, it did make a Press file directly, whereas TeX needs
an extra step to do that, though that program typically takes about a
tenth of the total time of the TeX run.  Also, no hyphenation was
going on (they're all short words in the test), so the fact that Tex
has a better, but slower, hyphenater didn't get measured.

One interesting thing was that Scribe produced 6 and a fraction pages of
output, while TeX produced 5 and a fraction.  Does that mean that TeX
runs `slower' than Scribe?  Of course not; rather than `seconds per page'
perhaps we should measure `microseconds per character'.

Another unfair part of this experiment was that it doesn't measure the
speed of any complicated formatting capabilities.  While these costs
are pretty standard from one Scribe user to the next, they vary more
among TeX users because folks use different macros, the efficiency of
which tend to vary greatly depending on the author.

On the other other hand, note that TeX is written in Pascal, while
Scribe (I am told) is written in Bliss.  The Pascal compiler used
on the 20 has many good features, but `quality, high-speed code' is
not among them.  The DEC 20 Bliss (I am told) served as a study in
implementing optimizing compilers.  Thus, we might expect to find
different results on, say, Vax/VMS, where the Pascal compiler is
quite good.

Indeed, on a Vax 782 (yes, 782) running VMS, I timed a run of the same
TeX and Scribe jobs (using SET CONTROL=T).  TeX took 20 CPU seconds,
while Scribe took 40.  Scribe was now outputting for the Imagen, and
this time it produced 8 and a fraction pages, so things aren't
directly comparable.

Finally, I moved the same input files to a Vax 780 running 4.? Berkeley
Unix.  This time Scribe chose to output in Press format again, but for
some reason it produced 8+ pages.  (TeX, of course, produced the identical
5+ page DVI file on each machine).  According to the "time" command in
/bin, TeX took "41.0 Real 30.9 User 2.1 Sys" while Scribe took "42.0 Real
35.8 User 2.3 Sys" time.  Interesting.

Disclaimers: Of course, I only did a few timings on each machine, and while
it was late at night, there were other things going on that may have skewed
the results.  Benchmarks never measure what you want them to.  I work for
Prof. Knuth's TeX project.

Plug: The TeXbook is now available at a bookstore near you.  Only $14.95!!

	-david
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