theprof00 said:
Xen said:
theprof00 said:
I had heard of another thing recently, but can't seem to find it again. Basically there was some kind of code that was being implemented by nvidia boards that made amds perform worse on benchmarks. |
Nvidia makes mobo chipsets still?
Somehow, I don't remember any new mobo or chipset from them. Ion doesn't count, if those are still popular (can't say I really follow those).
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It might not have been a board, but some kind of coding, tesselation or some such. I really don't remember. It was just something to do with benchmarks. Anyway, whatever the case may be, there was nvidia or intel coding (can't remember which) that would cause amds to perform worse than they should be.
Here's a quote I found:
"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."
It turns out that while this is known behaviour, few users of the Intel compiler actually seem to know about it. Intel does not advertise the compiler as being Intel-specific, so the company has no excuse for deliberately crippling performance on non-Intel machines.
"Many software developers think that the compiler is compatible with AMD processors, and in fact it is, but unbeknownst to the programmer it puts in a biased CPU dispatcher that chooses an inferior code path whenever it is running on a non-Intel processor," Fog writes, "If programmers knew this fact they would probably use another compiler. Who wants to sell a piece of software that doesn't work well on AMD processors?"
In fact, Fog points out that even benchmarking programs are affected by this, up to a point where benchmark results can differ greatly depending on how a processor identifies itself. Ars found out that by changing the CPUID of a VIA Nano processor to AuthenticAMD you could increase performance in PCMark 2005's memory subsystem test by 10% - changing it to GenuineIntel yields a 47.4% performance improvement! There's more on that here [print version - the regular one won't load for me].
In other words, this is a very serious problem."
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