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FP8 is ~100 tflops faster when the kernel name has "cutlass" in it

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Re: FP8 is ~100 tflops faster when the kernel name has "cutlass" in it

#41

So, what is Cutlass, can someone explain whether checking for kernel names makes sense here or is a form of cheating? https://docs.nvidia.com/cutlass/index.html

Github version: https://github.com/NVIDIA/cutlass

I wonder if we search the comments if we can find something referencing this.

Re: FP8 is ~100 tflops faster when the kernel name has "cutlass" in it

#43

Earlier quoted context omitted.

Or maybe Quack III: Arena. https://m.slashdot.org/story/21054

Now I want a Quake shooter but with ducks.

Not ducks, but chickens, was very popular in Germany back in the day: https://en.wikipedia.org/wiki/Crazy_Chicken

Re: FP8 is ~100 tflops faster when the kernel name has "cutlass" in it

#45

And what’s the downside of using that kernel name? It can’t just be that it’s faster and nothing else. Unless they included lots of sleep(x) calls.

There might be optimizations that are only safe for the code that this was an intender for.

Re: FP8 is ~100 tflops faster when the kernel name has "cutlass" in it

#46
post #3

GenuineIntel moment.

Or maybe Quack III: Arena. https://m.slashdot.org/story/21054

Aah, that brings back memories...

Interestingly, most benchmark controversies back in the day are now expected behaviour, i.e. game-specific optimizations with no (well, in this age of upscalers and other lossy optimization techniques, probably even somewhat) visible image degradation. A gaming-specific driver with no game-specific improvements in its changelog would be considered strange, and it very much works with executable detection.

Back in the day, there was still the argument that drivers should not optimize for benchmarks even when visually identical, because it wouldn't show the hardware's real world potential. Kinda cute from today's perspective. :)

But of course there were the obvious cases...

The Quack3 lowering filtering quality as shown above, of course (at least that one was put into the driver as a togglable setting later on).

But the most cheeky one has to be nVidia's 3dmark03 "optimizations", where they blatantly put static clip planes into the scenes so that everything outside the predefined camera path from the benchmark sequence would simply be cut from the scene early (which e.g. fully broke the freelook patched into 3dmark and would generally break any interactive application)

Re: FP8 is ~100 tflops faster when the kernel name has "cutlass" in it

#47
post #3

GenuineIntel moment.

Or maybe Quack III: Arena. https://m.slashdot.org/story/21054

Ooh, I remember this, but actually the thing is older than it.

First, nVidia and ATI used executable names for detecting games, then they started to add heuristics.

If you think they stopped the practice, you're very mistaken. Every AMD and nVidia driver has game and app specific fixes and optimizations.

nVidia cheated in 3D Mark that way, so they patched/changed their benchmark to prevent it. Also, again nVidia, patched their drivers so some of the more expensive but visually invisible calls like scene flushes in a particular game is batched (e.g. do all 50 flushes at the 50th call) to prevent the game becoming a slide show on expensive hardware.

This is also why AMDs and Intel's open source drivers under Linux a success, because they are vanilla drivers written from scratch per spec, and if your code calls OpenGL/Vulkan to spec, then you're golden.

Even some companies cross compile AMD's Linux drivers for windows on embedded systems since they're free from useless optimizations from them.

Re: FP8 is ~100 tflops faster when the kernel name has "cutlass" in it

#48
post #46

Earlier quoted context omitted.

Or maybe Quack III: Arena. https://m.slashdot.org/story/21054

Aah, that brings back memories... Interestingly, most benchmark controversies back in the day are now expected behaviour, i.e. game-specific optimizations with no (well, in this age of upscalers and other lossy optimization techniques, probably even somewhat) visible image degradation. A gaming-specific driver with no game-specific improvements in its changelog would be considered strange, and it very much works with…

You beat me to it. Grrr...

Just kidding, nice to see another person who remembers these things. Want some root beer?

Re: FP8 is ~100 tflops faster when the kernel name has "cutlass" in it

#50
post #9
post #8

Earlier quoted context omitted.

I'm interested in that story, what are you referring to with "GenuineIntel"?

Intel's C++ compiler is known to add branches in its generated code checking if the CPU is "GenuineIntel" and if not use a worse routine: https://en.wikipedia.org/wiki/Intel_C%2B%2B_Compiler#Support... .

Even in the middle of that turmoil, we managed to compile some code with Intel's ICC and make it go faster on AMD Opterons, breaking Intel's own numbers.

When my colleague said that they managed to go faster than intel with icc with some hand tuned parameters, I remember answering "youdidwat?".

Good times.

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