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Date: | Mon, 17 Jun 2002 09:34:21 EDT |
To: | Marcus Elderic Koenig <elderic AT t-online DOT de>, cygwin AT cygwin DOT com |
Subject: | Re: gcc 3.1 slower than 2.95? |
From: | Harold L Hunt <huntharo AT msu DOT edu> |
Marcus, First, this is probably way off topic for the Cygwin list. You should be asking on the gcc lists. However, I can make one comment. In a scientific experiment you only change one variable each time. However, you changed two: > -> gcc 2.95 > g++ -O2 -mcpu=pentium -Wall settest.cpp -lwinmm > > -> gcc 3.1 > g++ -O3 -mcpu=pentium -Wall settest.cpp -lwinmm You changed both the compiler (from 2.95 to 3.1) and the optimization flag (from -O2 to -O3). Don't do that. Make both tests at -O2 or -O3. The -O2 flag seems to be about as high as anyone goes without doing some extensive analysis on their own to determine if -O3 would be of any benefit. Also, the -O3 flag can do things that make the code size much larger which can negate the effect of a processor cache, etc. Stick with -O2 for both tests. Harold -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Bug reporting: http://cygwin.com/bugs.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
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