What is NCCL Window

Accelerated Computing GPU-Accelerated Libraries
1

I was reading the NCCL doc User Buffer Registration — NCCL 2.27.5 documentation

NCCL supports window registration, which allows users to register local buffers into NCCL window and enables extreme low latency and high bandwith communication in NCCL.

But what is exactly NCCL window? I didn’t find any explanation of NCCL window in the doc.

2

NCCL memory window follows the MPI RMA window model. A memory window is a defined region of memory that a process makes accessible to other processes for one-sided (RMA) operations such as remote put, get, etc. You can refer to https://doi.org/10.1145/2780584 for more details on MPI RMA window.