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Intel Prepares to Graft Google’s Bfloat16 onto Processors

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Re: Intel Prepares to Graft Google’s Bfloat16 onto Processors

#41

They're not really "grafting" it, they're implementing it as a first-class data type.

Definitely feels click-bait-y.

Ditto for them calling it "Brain Floating Point" [1]. I mean it appears to be a typical floating-point numeric data type with some of the precision truncated to reduce its cost.

I guess they might be trying to make it sound super-fancy to preempt people seeing it as cheap or/and low-tech?

[1]: https://en.wikipedia.org/wiki/Bfloat16_floating-point_format

Re: Intel Prepares to Graft Google’s Bfloat16 onto Processors

#42

English is not my first language. I have never heard the term "Graft", even if I consider myself quite literate in English. So here you go, for everybody else in my situation: Graft, as understood in American English, is a form of political corruption, being the unscrupulous use of a politician's authority for personal gain. Edit: by the way, I really couldn't fit the term with the article. And realized I was probabl…

I believe this version is more relevant: "transplant (living tissue) as a graft."

Re: Intel Prepares to Graft Google’s Bfloat16 onto Processors

#43
post #7
post #6

I am sorry for Intel. Perhaps John Gustafson’s 16 bit posits or unums would have made a better choice.

Why? Google has certainly researched their floats before committing an entire line of silicon chips. It's easy to just enumerate all possible float16 configurations in a simulator to see which one performs best on a wide range of neural network applications. Then pick the best one. Big data driven organizations do this all the time (brute force through an entire line of solutions, pick best results).

bfloat16 is "best" primarily because it has the same exponent range as float32. That makes it easy to port models that have been developed using float32 to bfloat16. (As opposed to using int8 or float16, both of which have a smaller exponent range.)

It's possible that some other custom format is better in absolute terms for models trained specifically for the custom format. But for the current ecosystem, where models are trained primarily using float32, bfloat16 is a very good choice.

Re: Intel Prepares to Graft Google’s Bfloat16 onto Processors

#44

English is not my first language. I have never heard the term "Graft", even if I consider myself quite literate in English. So here you go, for everybody else in my situation: Graft, as understood in American English, is a form of political corruption, being the unscrupulous use of a politician's authority for personal gain. Edit: by the way, I really couldn't fit the term with the article. And realized I was probabl…

That definition definitely does not apply to this usage. You are looking for "to join (one thing) to another as if by grafting, so as to bring about a close union." (etymology 1, verb, definition 4 on Wiktionary [1]).

[1] https://en.m.wiktionary.org/wiki/graft

Re: Intel Prepares to Graft Google’s Bfloat16 onto Processors

#45

English is not my first language. I have never heard the term "Graft", even if I consider myself quite literate in English. So here you go, for everybody else in my situation: Graft, as understood in American English, is a form of political corruption, being the unscrupulous use of a politician's authority for personal gain. Edit: by the way, I really couldn't fit the term with the article. And realized I was probabl…

insert or fix (something) permanently to something else, typically in a way considered inappropriate.

This is the definition they most likely meant.

Re: Intel Prepares to Graft Google’s Bfloat16 onto Processors

#46
Why "graft"? It's not something that's foreign to them. This promises to essentially double the performance of Intel chips on an increasingly important workload, and also simplify the modeling work, because the models don't experience any accuracy drop when simply converted to bfloat16, unlike with quantization, where it's model dependent and finicky AF. I'd much rather do fp16 or bfloat16 at inference time, without constant pain that is quantization. I hope ARM, AMD and RISCV pay attention and implement this in the exact same way, so that models could be portable.

Re: Intel Prepares to Graft Google’s Bfloat16 onto Processors

#47
post #41

They're not really "grafting" it, they're implementing it as a first-class data type.

Definitely feels click-bait-y. Ditto for them calling it "Brain Floating Point" [1]. I mean it appears to be a typical floating-point numeric data type with some of the precision truncated to reduce its cost. I guess they might be trying to make it sound super-fancy to preempt people seeing it as cheap or/and low-tech? [1]: https://en.wikipedia.org/wiki/Bfloat16_floating-point_format

It's called brain floating point because it was developed by Google's "Google Brain" machine learning project.

Re: Intel Prepares to Graft Google’s Bfloat16 onto Processors

#48
post #36

Earlier quoted context omitted.

Yes, there’s a bios setting to control this. It basically under clocks the core while AVX units are under load.

Taking my 7980xe as an example: When it runs non-avx512 loads, I currently have it set to run at 4.1 GHz (all-core). When running avx-512 heavy loads, it instead runs at 3.6 GHz -- and tends to get much hotter (70-80C instead of 50-60C). 3.6 GHz is a mild overclock; Silicon Lottery reports 100% can achieve that speed for avx512 loads.[1] Running programs doing the same thing (eg, Hamiltonian Monte Carlo where the lik…

Yeah, people tend to completely exaggerate the impact of throttling from AVX512. It's only an issue when you do short bursts of AVX512 and the rest is not AVX512. If you do math and your math can be done in AVX512, even with throttling it's going to be substantially faster. That it runs hotter doesn't concern me at all. Intel's claimed safe Tjunction is something like 105C. EEs tend to take the published component specifications seriously (e.g. your 1000v diode is guaranteed to withstand at least 1KV of reverse voltage), so I trust Intel when they say things are fine up to that temperature. Even beyond that it won't burn out, it'll just thermal throttle.

Re: Intel Prepares to Graft Google’s Bfloat16 onto Processors

#49
post #41

Earlier quoted context omitted.

Definitely feels click-bait-y. Ditto for them calling it "Brain Floating Point" [1]. I mean it appears to be a typical floating-point numeric data type with some of the precision truncated to reduce its cost. I guess they might be trying to make it sound super-fancy to preempt people seeing it as cheap or/and low-tech? [1]: https://en.wikipedia.org/wiki/Bfloat16_floating-point_format

It's called brain floating point because it was developed by Google's "Google Brain" machine learning project.

Yeah, I get the marketing perspective; just, we typically describe primitive data types in terms of what they are from a technical perspective rather than a marketing perspective.

Re: Intel Prepares to Graft Google’s Bfloat16 onto Processors

#50
post #46

Why "graft"? It's not something that's foreign to them. This promises to essentially double the performance of Intel chips on an increasingly important workload, and also simplify the modeling work, because the models don't experience any accuracy drop when simply converted to bfloat16, unlike with quantization, where it's model dependent and finicky AF. I'd much rather do fp16 or bfloat16 at inference time, without…

I read this article as saying, "hey we can emulate bfloat16 pretty well in software on top of our existing hardware features". That's what "graft" and "minimal impact" mean to me.

Intel (for better or worse) takes a very experiment-results-driven approach to choosing which features to implement in hardware. So this result -- that software emulation of a feature works almost as well as a hardware implementation would -- probably makes Intel less likely to implement the feature in hardware.

ARM, AMD, RISCV etc, will probably come to similar conclusions.

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