Comment by zgao
5 hours ago
Chip CEO here. It really depends on what "design" or "production" means. Does "design" mean that the design was complete? Does "production" mean the beginning of production, i.e. tapeout? If measuring from RTL-freeze to tapeout, this is a fairly typical (even somewhat unimpressive) timeline (accounting for some unexpected issues) for a large, complex 3nm chip. If measuring from concept (no RTL at all, block diagram of architecture) to tapeout, this is an amazing timeline. The truth is probably somewhere in between. A more concrete statement would use actual technical milestones and gates.
Not a chip CEO, but I read this article and thought that they're working on some kind of application specific chip only for serving models. Similar to how an FPGA can optimize certain tasks.
Given constant weights / biases of a Transformer / DNN you could use pipelining to feed forward calculations through the array one layer at a time. For DNN's with thousands of layers you might see 1:1 speed up per layer channel.
I doubt they would undergo this process for marginal gains.
Yes, my statement was not about the quality or performance of the chip -- simply the tapeout timeline that was stated, by itself.
i don't understand what the second paragraph is saying.
In very crude terms, AFAICT, if you have a bunch of matrix multiplications, but one of matrices (the one with model weights) doesn't change, you can seriously speed up the computation. One thing is that you don't need to re-fetch the elements of the constant matrix, you can keep it near the ALUs. Then you maybe can detect and ignore sparse / empty blocks by marking them once.
IDK how the custom hardware exploits this; would love to hear any ideas!
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Basically getting around the branch predictor problem with generalized compute architectures https://en.wikipedia.org/wiki/Branch_predictor
>If measuring from RTL-freeze to tapeout, this is a fairly typical (even somewhat unimpressive) timeline (accounting for some unexpected issues) for a large, complex 3nm chip.
Even for a company’s first design?
I don't think you get the newcomer novelty buff when your val approaches 13 digits.
Big companies are lumbering behemoth, crude assemblages of barely cobbled-together incentives and principal agent problems in a trenchcoat. Getting them to change direction, or worse, try something new at scale, is a massive undertaking
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The typical way a chip effort in a non-chip company works is that the "design" is the RTL (e.g. SystemVerilog that defines the behavior of the chip) and then this is handed off to a third-party "design house" (such as Broadcom) that turns that code into a real image of a chip, which is called a GDS (basically you can think of this as a very big layer by layer photoshop file) that can actually be sent to a fab. This is called "backend design", in contrast to the "frontend design" (the RTL itself).
As another commenter said, Broadcom is very experienced with backend design (as well as the supply chain management, testing, etc. that comes after the chip is taped out) and so this can't be regarded as a "first chip". Richard Ho (the head of hardware at OpenAI) is also extremely experienced and used to be the head of the Google TPU effort -- where he actually worked with Broadcom in a similar tapeout already. So yes, this is not a "first design"!
This isn't Broadcom's first design.
Yeah, "first chip" here likely means they contracted Broadcom (or a firm with similar experience) to do all the heavy lifting. Building out your own in-house teams for this sort of thing is a decade-long project - just look how much inside Apple's early chips was licensed ARM / PowerVR cores
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