Performance issues with recent compilers

Performance issues with recent compilers

We accidentally discovered that our C++ code runs slow when compiled with the 7.1 compiler (as compared to the 5.0 compiler). I was using staticly-compiled binaries for all tests. Here are some numbers:

Compiled under RH7.2 with 5.0.1 compiler:
262.650u 0.310s 4:22.97 99.9% 0+0k 0+0io 48pf+0w

Compiled under RH9 (glibc-2.2.93) with 7.1 compiler:
304.980u 0.400s 5:05.50 99.9% 0+0k 0+0io 53pf+0w

Compiled under RH9 (glibc-2.3.2) with 7.1 compiler:
304.230u 0.430s 5:04.68 99.9% 0+0k 0+0io 53pf+0w

So the new compiler produces binaries that run 10-20% *slower* than the old compiler. What gives? Has anyone else seen this?

By the way, the binaries are always beating gcc. I can probably provice source if needed (have to check with the users first).

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For more complete information about compiler optimizations, see our Optimization Notice.

7.1 in a beta stage. Use 7.0 ;-)

Please note that Red Hat Linux 9 is not a supported by the Intel C++ Compiler for Linux 7.1

The 7.1 compiler is a product release and it is not a beta compiler.

It would be best that you submit an issue to Intel Premier Support,

If you have not created a Premier Support account, please go to the registration center, Both Premier Support and the Registration Center use the same account.

Thank you,

Elizabeth S.
Intel Customer Support

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