Subject: More on Pentium gcc
To: None <port-i386@NetBSD.ORG>
From: Jeff Thieleke <thieleke@lust.isca.uiowa.edu>
List: port-i386
Date: 04/21/1996 16:37:24
I finally set up some automated tests to see how well pgcc really works,
especially at different optimization levels. I have a whole spreadsheet
full of numbers, but here is a quick summary. The first percentage is the
improvement over gcc -O2 -m486 for gzip -9, and the second is the
improvement for decompression.
Using a pgcc -O2 compiled kernel:
pgcc -O4 -O3 -O2
5%, 7.85% 3.58%, 12.99% 3.03%, 8.75%
(I was lazy and used a single pgcc -O2 compiled libgnumalloc, so the -O4
and -O3 percentages might be a bit low)
I'm not overally impressed with the numbers, and I ran into my first pgcc
related problem. After building an entire pgcc -O3 system, I found that
awk dumped core consistantly. So I rebuilt using -O2, and everything
seems fine now (although I am still using a -O3 kernel with seemingly no
problmes).
The moral: if you use pgcc, use -O2 and don't expect massive speed
improvements.
Jeff Thieleke