On Mon, 2 Jul 2018, Dennis Dalessandro wrote: > Omni-Path TID RDMA Feature > > Intel Omni-Path (OPA) TID RDMA support is a feature that accelerates data > movement between two OPA nodes through the IB Verbs interface. It improves > RDMA READ/WRITE performance by delivering the data payload to a user > buffer directly without any software copying. Well that is what RDMA already does and that is the reason RDMA technology was implemented. What does TID do? Searched for information about TID and could not find much aside from vague statements in Intel manuals. > Architecture > ============= > The TID RDMA protocol is implemented on the hfi1 driver level and is > therefore transparent to the ULPs. It is designed to facilitate the data > transactions for two specific RDMA requests: > - RDMA READ; > - RDMA WRITE. > Previously, when a verbs data packet is received at the destination (requester > side for RDMA READ and responder side for RDMA WRITE), the data payload > is copied to the user buffer by software, which slows down the performance > significantly for large requests. The RDMA technology that we do have here definitely does not use software to copy the data. Are we talking about a driver that falls back to software handling that you are trying to fix? > For TID RDMA requests, hardware resources (hardware flow and TID entries) > are allocated on the destination side (the requester side for TID RDMA > READ and the responder side for TID RDMA WRITE). The information for > these resources is conveyed to the data source side (the responder side > for TID RDMA READ and the requester side for TID RDMA WRITE) and embedded > in data packets. When data packets are received by the destination, > hardware will deliver the data payload to the destination buffer without > involving software and therefore improve the performance. Well you register RDMA memory and thus reserve the resources and you may call that allocation of resources too... What in the world is this? Reimplementing RDMA on top of RDMA? -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
