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Re: Massive performance regression from switching to gcc 4.5


On Fri, 25 Jun 2010, it was written:
> On Thu, Jun 24, 2010 at 11:50:52AM -0700, Taras Glek wrote:
> > We switched gcc4.3 for gcc4.5 and our automated benchmarking
> > infrastructure reported  4-19% slowdown on most of our performance
> > metrics on 32 and 64bit Linux.
>
> Could you please also try gcc4.4, so that it is clear if the slowdowns
> are between 4.3 and 4.4 or 4.4 and 4.5?  Would be nice to narrow the changes
> a little bit.

There sure is something in 4.5. I've seen a 1-10% slowdown at the GiNaC
(a computer algebra library) benchmark suite after switching from 4.4 to
4.5 on x86_64 when compiling with -O2. And there hasn't been a measurable
performance differences between 4.3 and 4.4.

  -richy.
-- 
Richard B. Kreckel
<http://www.ginac.de/~kreckel/>


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