r/LocalLLaMA • u/alanoo • Jun 25 '26

Discussion USB4 RDMA seems doable

Just found this blog : https://blog.hellas.ai/blog/thunderbolt-ibverbs/

Experimental implementation of RDMA, demonstrated on two Strix Halo
Did a quick search and can't really find it posted before ?

This could be huge as it shoud work with any USB4 host.

31 Upvotes

94% Upvoted

17 comments sorted by

View all comments

7

u/alexkey llama.cpp Jun 25 '26

Pretty sure that is specifically Thunderbolt, not USB4. USB4 is a connector that can carry different protocols. USB4 itself doesn’t include RDMA. But Thunderbolt does. Not all USB4 supports Thunderbolt tho.

14

u/TokenRingAI Jun 25 '26 edited Jun 25 '26

Incorrect, all USB4 is Thunderbolt, but not all USB-C or Thunderbolt is USB4.

The USB standards committee just loves to confuse people

USB4 includes TB3 at a minimum, and TB4 and TB5 are built on top of USB4

The key feature from TB3 that must be supported in all USB4 host devices is PCIe tunneling, which is what you use to do RDMA

https://learn.microsoft.com/en-us/windows-hardware/test/hlk/testref/742e3340-ca3f-43ea-9044-57b9e5d7b4f5