[DDP][Instrumentation] Profiling range for bucket copy (#65769)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/65769
Seeing some bottlenecks when copying bucket to grad, help make it more
clear here.
ghstack-source-id: 139838597
Test Plan: Ci
Reviewed By: zhaojuanmao, wayi1
Differential Revision: D31217340
fbshipit-source-id: 762a254a3538eb5292b3a53bb5d1211057ecbdbb
