Does uccl work with NVlink and other questions.

[whatdhack]

1. Does uccl work with NVLink and other scaleup networks ? If so, what are currently supported and what are in the road map.
2. How comprehensive us uccl in collectives support ?
3. Currently suppoertd GPUs/accelerators are Nvidia and AMD. Is there a porting document for new devices?

[YangZhou1997]

1. UCCL has three parts: collective, p2p, and EP. All three support NVLink. UCCL's main innovation is on RDMA usage, for example, UCCL-collective just leverages NCCL/RCCL for intra-node nvlink.
2. UCCL is a network plugin layer for NCCL, so support all NCCL collectives.
3. I think that would heavily depend on specific devices. Most of time, the difficulty is in the kernel programming, but not on UCCL portability.

[whatdhack]

@YangZhou1997 , another question. Do you think you can comment on uccl vs ctran from Meta ?

[YangZhou1997]

I think ctran uses the same multi-QP dynamic load balancing idea from uccl-collective (ctran was released half a year later than uccl-collective). Uccl-P2P and Uccl-EP target more applications like KVcache transfer and EP

[whatdhack]

Thanks, any thought on RoCEv2 , UAL, and UEC support ?

[YangZhou1997]

Uccl already supports Rocev2 and IB via libibverbs, eg, AMD UEC NICs. As long as they are libibverbs compatible, they could be supported.