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L'Ancien Regime

Intel coerced Cinebench to make AMD lose in their tests

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Thats interesting. Good thing I only look at two realworld benchmarks when buying a pc. Vray render  and Lightwave render benchmarks. :D

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http://www.agner.org/optimize/blog/read.php?i=49#49

 

This issue is getting more and more absurd the more I dig into it. AMD makes a function library called AMD Core Math Library (ACML) to match Intel's Math Kernel Library (MKL). I have tested a Windows version of ACML and found that some of the functions run faster when the CPU vendor ID is artificially changed to "GenuineIntel". Maybe this is not so surprising after all, since this version of ACML is compiled with Intel's Fortran compiler.

 

 

Common math programs are affected
 Intel are putting themselves into an advantageous position by making better function libraries than everybody else, and they are taking advantage of this position by lowering the performance of common mathematical software on the CPUs of their competitors relative to their own. We have probably not seen the end of the legal battles yet.

Edited by L'Ancien Regime

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Workarounds

At present, we don't know if or when Intel will make a new compiler and new software libraries that do not check the vendor ID string. In the meantime, here is what we can do about the problem.

  • Use another compiler. In my tests, the Gnu compiler for Linux has an optimizing performance similar to the Intel compiler, but the Gnu function library (glibc) is inferior. All other compilers gave lower performance in my tests. There is no other Windows compiler with a similar performance, not even the Gnu compiler for Windows.

      

  • Use the Intel software and patch the CPU dispatcher. In my C++ manual, I have provided the code for alternative CPU dispatchers for Intel's compiler and function libraries and descriptions on how to patch them into your software. This, of course, relies on undocumented details of the Intel software. This dispatcher-patch can improve performance on non-Intel processors considerably in many cases.

      

  • Never trust any benchmark unless it is open source and compiled with a neutral compiler, such as Gnu or Microsoft.

       

  • It is possible to change the CPUID of AMD processors by using the AMD virtualization instructions. I hope that somebody will volunteer to make a program for this purpose. This will make it easy for anybody to check if their benchmark is fair and to improve the performance of software compiled with the Intel compiler on AMD processors.

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Thats interesting. Good thing I only look at two realworld benchmarks when buying a pc. Vray render  and Lightwave render benchmarks. :D

 

That's the way to go. Benchmarks are irrelevant with today's marketing schemes. Even samsung is cheating in some benchmark for mobile (!) cpu's....

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On 8/6/2013 at 2:30 AM, L'Ancien Regime said:

http://www.agner.org/optimize/blog/read.php?i=49#49/writemyessay

This issue is getting more and more absurd the more I dig into it. AMD makes a function library called AMD Core Math Library (ACML) to match Intel's Math Kernel Library (MKL). I have tested a Windows version of ACML and found that some of the functions run faster when the CPU vendor ID is artificially changed to "GenuineIntel". Maybe this is not so surprising after all, since this version of ACML is compiled with Intel's Fortran compiler.

 

Common math programs are affected
 Intel are putting themselves into an advantageous position by making better function libraries than everybody else, and they are taking advantage of this position by lowering the performance of common mathematical software on the CPUs of their competitors relative to their own. We have probably not seen the end of the legal battles yet.

Hello,

I guess one more issue is SSSE3/SSE4.2 requirement that is made when the games are released (practically it's an issue for those who choose Phenom II line of AMD processors are some of the best processors which do not support SSSE3). I own a Phenom II 1100T 6X and I'm thinking to downgrade to something slower.

Sorry for bumping.

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