Re: Better performance on older version of GCC

[Corey Kasten <corey@materialintelligencellc.com>]

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On Fri, 2010-08-27 at 06:50 -0700, Nathan Froyd wrote:
> On Fri, Aug 27, 2010 at 09:44:25AM -0400, Corey Kasten wrote:
> > I find that the executable compiled on system A runs faster (on both
> > systems) than the executable compiled on system B (on both system), by a
> > factor about approximately 4 times. I have attempted to play with the
> > GCC optimizer flags and have not been able to get System B (with the
> > later GCC version) to compile code with any better performance. Could
> > someone please help figure this out?
> 
> It's almost impossible to tell what's going on without an actual
> testcase.  You might not be able to provide the actual code, but you
> could try distilling it down to something you could release.
> 
> -Nathan

Thanks for the reply Nathan.

I have attached an archive with the test case code. The code is built by
build.sh and outputs the number of microseconds to complete the
processing.

Compiling with GCC version "4.1.2 20070925 (Red Hat 4.1.2-33)" produces
code that runs in about 66% of the time than does GCC version "4.3.0
20080428 (Red Hat 4.3.0-8)"

Thanks

Corey

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