This is the mail archive of the
gcc-bugs@gcc.gnu.org
mailing list for the GCC project.
[Bug c++/14563] octave built under Cygwin very slow
- From: "Ben dot Diedrich at noaa dot gov" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 24 Mar 2004 21:07:46 -0000
- Subject: [Bug c++/14563] octave built under Cygwin very slow
- References: <20040312233606.14563.paulthomas2@wanadoo.fr>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From Ben dot Diedrich at noaa dot gov 2004-03-24 21:07 -------
Subject: Re: octave built under Cygwin very slow
Paul Thomas wrote:
> We ran a small test programme in octave that shows a factor of
> approximately 6 difference in execution time, when octave is built with
> gcc-3.2 (~1.8-2s) or gcc-3.3 (10-12s). When compiled and linked with
> -pg set, the execution time increased to 9s with gcc-3.2 (Ben, what is
> the corresponding figure for gcc-3.3?). Switching off the -O2 flags,
> increased the time by a further 3s but resulted in a much more detailed
> profile. In the enclosed, we increased the number of loops by a factor
> of 10, in order to get a reasonable resolution on the less frequently
> visited functions. So remember that the corresponding wall-clock time
> is 90s for cycle 2.
>
The execution time of Octave 2.1.50 with profiling turned on and GCC 3.3.1 was ~280 seconds. That is with the test command:
a = cputime ; tot = 0 ; x = [1:1e6] ; for i = 1:1e6 ; tot = tot + x(i) ; end ; disp(cputime-a)
The time is ~28 seconds with 1e5 for loop steps.
Ben
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14563