What does the Metric “global_reduction_request” mean? My experiment shows it is caused by the atomicAdd op in my code. So does the global_reduction_request mean the number of atomic write request to global memory?
Metric “global_reduction_request” provides total number of global reduction requests from Multiprocessor (SM). For reduction requests compiler generates the instruction RED, you can dump the SASS code using cuobjdump and check whether it shows the RED instruction for atomicAdd in the output.