NVIDIA Nsight Systems is a system wide profiler. It reads performance counters coming from CPUs, GPUs, NICs, storage volumes, etc. and brings all data to a unified timeline. This helps software developers see how their application executes over a server, to be able to optimize the application's performance.

Additional details are at:

• https://developer.nvidia.com/nsight-systems 
• https://docs.nvidia.com/nsight-systems/UserGuide/index.html 

Nsight Systems reads Lustre client performance counters from /sys/kernel/debug/lustre/llite/<volume name>/stats

However, when data is read/written to a file mapped to memory using mmap, the traffic isn't reflected in the stats file.