What Is NVLink? And How Will It Make the World’s Fastest Computers Possible?

blogs.nvidia.com

12 points·eslaught··3 comments

As far as I can tell, this is a replacement for PCIe for connecting a GPU to a computer. Does this mean there will be a new connector for connecting a GPU, or are GPUs expected to be soldered to the board?

Is NVLink attached to the northbridge, or is it a replacement for the northbridge? Is the northbridge even a thing in computer architectures this large?

I think NVlink is a re-configuration of the PCIe standard, while using the same physical pathways it communicates in a different way.

Currently PCIe can talk directly to the memory controller, and have direct RAM access without CPU overhead. So the whole GPU's run as fast as CPU's can give them memory is a bit false (but since memory controllers are on chip now I guess its true?).

What this maybe, if I had to guess. Is dynamic lane allocation. Where 1 GPU can free its PCIe lanes to let other devices use them. So 1 GPU can use all ~90 or how ever PCIe lanes IBM power9 chips have, instead of 4 GPU's each having 22.

The only real similarity to PCIe is that they're both high-speed differential signaling standards. This article has a good overview of what is known: http://www.anandtech.com/show/7900/nvidia-updates-gpu-roadma... .

For an example of what the signaling might look like, see https://research.nvidia.com/publication/054-pjb-20-gbs-groun...

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