From: fabio AT joplin DOT colorado DOT edu (Fabio Somenzi) Subject: Re: Runtime speed with GNU compilers 13 Apr 1997 11:19:50 -0700 Approved: cygnus DOT gnu-win32 AT cygnus DOT com Distribution: cygnus Message-ID: <199704131657.KAA10542.cygnus.gnu-win32@joplin.colorado.edu> Original-To: stefano AT tirreno DOT it Original-Cc: gnu-win32 AT cygnus DOT com Original-Sender: owner-gnu-win32 AT cygnus DOT com Stefano Gragnani writes: ->I have downloaded and installed under Windows NT 4.0 the latest Cygnus ->GNU-Win32 software. All work fine but the time of execution is very very ->slow. For example: [snip] ->For this we obtain 2062 seconds !!! (My machine is a PentiumPro 200 MHz, ->128 MB RAM) ->With the same code if compiled with the old Borland c++ 4.0 we obtain 219 ->seconds and with cross-compilation (Metrowerks CodeWarrior 11 compiler ->under PowerMacintosh) we obtain 125 seconds. -> ->I have not experience with GNU compilers (is the first time I used it), I ->have compiled and linked the file with the command: -> ->g++ -o3 trigtest.cpp -> ->If I well understood the '-o3' option optimize for speed. Try g++ -o trigtest -O6 -ffast-math trigtest.cc (Note the capital "O".) On my P6 200MHz running Linux it takes 117 seconds. Without the -ffast-math it takes 165 seconds. The -ffast-math option allows the compiler to take some liberties with respect to the IEEE 754 standard. I'm running the same example on my 120 MHz P5 laptop running Win95 and it's taking a while. (More than 2000 seconds.) It's better to compare numbers from the same machine. But there may be a problem with GCC under cygwin in this instance. The problem may be in the libraries. Hope this helps. Fabio -- Fabio Somenzi | Phone: 303-492-3466 University of Colorado | Fax: 303-492-2758 ECE Dept. | Email: Fabio AT Colorado DOT EDU Boulder CO 80309-0425 | WWW: http://vlsi.colorado.edu/~fabio - For help on using this list (especially unsubscribing), send a message to "gnu-win32-request AT cygnus DOT com" with one line of text: "help".