> kumar...@gmail.com wrote:

>> hello:

>

>> I recently compiled a numerically intensive c project under cygwin gcc
>> 3.4.4 and microsoft visual c. The platform is intel T2400 1.83 ghz
>> dual core lap top.

>

>> the numerical stuff is both floating point and integer intensive

>

>> The gcc optimized (-O3) vs non optimized improved the performance 30 %%

>
> The more you go with higher optimizations, the slower
> it goes. Use -O2.
>

>> visual c optimized (standard , check 'release; under visual c 2005)
>> vs non optimized ('build') was a whopping 8x performance gain

>
> This is because the non optimized version injects a lot of
> checking code to avoid bugs. It is slower than strictly necessary.
> For instance they check at function exit if there wasn't a stack overwrite.
>

>> but the most surprising thing was visual c optimized was 2x
>> performance over gcc optimized.

>
> Intel compiler is even better than Microsoft. It is the best compiler
> for the intel architecture. Period.
>

>> is anybody else seeing the same thing. if this is true microsoft c
>> compiler is in a different league altogether

>
> Obviously Microsoft leaves gcc far behind, and I have been seeing this
> since at least 8-9 years.
>

>> i was not successful so far compiling under mingw. will it make dent ?
>> 2x is hard to overcome

>
> mingw is just gcc using Microsoft run time library. Do not expect
> anything better/worst.
>
> It is not surprising that gcc is slower than Microsoft since the
> people behind each project have vastly different objectives and
> budgets to implement them.
>
> Gcc is running in many platforms and architectures.
> Microsoft is running in one platform exclusively.
>
> Gcc implements standards like C99 (module small problems), Microsoft
> implements only Microsoft  environments (.net, etc). Microsoft is
> still at C89 level.
>
> --
> jacob navia
> jacob at jacob point remcomp point fr
> logiciels/informatiquehttp://www.cs.virginia.edu/~lcc-win32