icpc on Linux compile time MUCH longer than g++

icpc on Linux compile time MUCH longer than g++

Hi!

I'm currently evaluating Intel compiler (V 7.0 Bld 20021021Z) to be used with a large simulation code developed at SKF. RedHat 7.2 and glibc-2.2.5-42 running on dual-proc Athlon MP 1.2G is used.

For some files (major part of the source) icpc takes much longer than g++ (4 minutes instead of 7 seconds).
The options used: icpc -g -tpp6 -I<...> -c<..>
The compiler generates a list of warnings and then freezes with mcpcom taking 100% CPU time.

Questions:
Have someone seen such behaviour? Are there any guidelines on searching for the problem? Is it possible to detect the stage of the compiler that takes so long time (e.g., produce a log)?

TIA, Iakov

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Para obtener más información sobre las optimizaciones del compilador, consulte el aviso sobre la optimización.

I would like to know the options you used with GNU compiler (gcc).

The default optimization option for Intel compiler is O1, whereas it is O0 (optimization is disabled) for gcc.

This could be the reason for the difference in compile time.

Regards,
CP

I used "-g" in both cases which implies -O0.

Actually, I started from -O3, didn't like the long compile time, gradually went down to -O0 without any significant changes in compile time.

Hope the problem is fixed in 7.1. BTW where can I download the update? It's only 7.0 on FTP...

/Iakov

Is it possible for you to attach the preprocess file for one such source file (taking 7 secs with g++ and 4 min with Intel compiler) ?

Regards,
CP

I'm sorry, but this is not possible since parts of the code are confidential. Other thing - the preprocessed file is almost 1MB large (150K after gzip).

If you have some ideas of what I can try I'll appreciate you sharing them with me.

TIA, Iakov

First I want to make sure that you are using only "-O0 -g" to compile source files.
I have compiled many open source applications with Intel and GNU compiler, but never seen such a huge difference in compile time.

Compiler can do some template processing even at compile time and it is possible that Intel compiler is spending most of its time in template instantiation. We have noticed this behaviour of Intel compiler with Pooma.

Regards,
CP

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