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LeoNatan
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 Posted: Fri, 8th Jan 2010 02:00 Post subject: Intel Forced to Remove "Cripple AMD" Function from |
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| Quote: | Here's something you probably don't know, but really should - especially if you're a programmer, and especially especially if you're using Intel's compiler. It's a fact that's not widely known, but Intel's compiler deliberately and knowingly cripples performance for non-Intel (AMD/VIA) processors.
Agner Fog details this particularly nasty examples of Intel's anticompetitive practices quite well. Intel's compiler can produce different versions of pieces of code, with each version being optimised for a specific processor and/or instruction set (SSE2, SSE3, etc.). The system detects which CPU it's running on and chooses the optimal code path accordingly; the CPU dispatcher, as it's called.
"However, the Intel CPU dispatcher does not only check which instruction set is supported by the CPU, it also checks the vendor ID string," Fog details, "If the vendor string says 'GenuineIntel' then it uses the optimal code path. If the CPU is not from Intel then, in most cases, it will run the slowest possible version of the code, even if the CPU is fully compatible with a better version."
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In other words, this is a very serious problem. Luckily, though, it appears that the recent antitrust settlement between AMD and Intel will solve this problem for at least AMD users, as the agreement specifically states that Intel must fix its compiler, meaning they'll have to fix their CPU dispatcher.
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This is a particularly nasty kind of anticompetitive practice, as it really requires deep knowledge of matters in order to find it out. God knows how many benchmarks have been skewed in favour of Intel simply because people unknowingly used Intel's compiler in good faith. Intel's compiler is seen as the cream of the crop and delivers superior performance, but apparently only if you stick to GenuineIntel. |
The rest of the article: Source
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SuTuRa
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Nui
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Location: in a place with fluffy towels
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| Posted: Fri, 8th Jan 2010 04:44 Post subject: |
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hey..intel should work with nvidia.
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nerrd
Posts: 3607
Location: Poland / USA
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| Posted: Fri, 8th Jan 2010 08:32 Post subject: |
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^ lol. was thinking the same.
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| Posted: Sat, 9th Jan 2010 12:44 Post subject: |
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I dont think it`s intention. every manufacturer of cpus would try to optimize for its own chips.
and this is known among developers. so - no problem. AMD could make their own compilers, couldnt they?!
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Nui
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Location: in a place with fluffy towels
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| Posted: Sat, 9th Jan 2010 14:11 Post subject: Re: Intel Forced to Remove "Cripple AMD" Function |
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| iNatan wrote: | | Quote: | | "However, the Intel CPU dispatcher check[s] which instruction set is supported by the CPU, it also checks the vendor ID string," [...] If the CPU is not from Intel then, in most cases, it will run the slowest possible version of the code, even if the CPU is fully compatible with a better version." |
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optimizing for their own chips, of course. But this seems to take the slowest possible code if the cpu is from amd
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LeoNatan
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Location: Ramat HaSharon, Israel 🇮🇱
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| Posted: Sat, 9th Jan 2010 14:21 Post subject: |
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No no, you need to be aware on the whole picture. Intel uses artificial checks to determine whether the CPU ID contains GenuineIntel; if so, it uses the most advanced extensions available for the CPU for optimizations. If the string is not found, the compiler deliberately uses not optimized paths even though AMD CPUs support the same extensions. This has been proven by reverse engineering the compiler and removing the artificial check.
Edit: Nui said it too. 
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| Posted: Sat, 9th Jan 2010 15:04 Post subject: |
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wonder how much intel is paying out to keep this as quiet as possible. It's hitting big over at overclock.net
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