[Bug c++/14563] octave built under Cygwin very slow

[Ben dot Diedrich at noaa dot gov]

------- 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



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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14563