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List:       kde-devel
Subject:    Re: dynamic_cast performance overhead
From:       Lubos Lunak <l.lunak () suse ! cz>
Date:       2005-06-03 8:57:37
Message-ID: 200506031057.37320.l.lunak () suse ! cz
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On Thursday 02 of June 2005 19:34, Sunil wrote:
> Hi,
>
> First email in this forum and new to kde code, so
> please excuse me if I am off the mark.
>
> I have noticed that dynamic_cast can add a LOT of
> overhead to the runtime execution, particularly on
> platforms where g++ doesn't do a good job. So, I
> started a little exercise to figure out if there were
> places in KDE code where it wasn't needed but was
> present. I pick this for a random example (may be not
> the critical path, but nonetheless):
...
>
> Is there any effort on part of the kde community to
> re-look at this aspect of the source code and see if
> some developers went overboard with dynamic_cast?
>
> Thanks,
> Sunil
> PS:Startup times for KDE are upto 2-3 times faster
> without certain dynamic_cast operations present in the
> code on cygwin (probably one of the platforms where
> g++ doesn't do a good job with rtti).

 I somehow doubt this, dynamic_cast on cygwin would have to be REALLY bad for 
tripling KDE startup time. Are you sure your benchmarks were correct and that 
you e.g. haven't done one with cold caches and the other with data already 
precached?

-- 
Lubos Lunak
KDE developer
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