Definition
Plain language
A tool that shows the timeline of what a program does across a whole system, spotting gaps where the graphics chip sat idle.
As stated in the literature
NVIDIA Nsight Systems, a system-wide GPU/CPU timeline profiler used to surface launch overhead and idle gaps between operations; paired with ncu and SASS disassembly in KernelPro's profiling stack.
Why it matters: It shows the whole timeline of a program's activity, exposing wasted gaps and startup delays that a narrower look at the chip alone would miss.
For example, nsys can reveal that a graphics chip sat idle between two steps because the program was slow to hand it the next batch of work.
Heard on the show
“The second, nsys, sees the system timeline — launch overhead, gaps where the GPU just sat idle between jobs.”Episode 177 — Why Raw Profiler Data Made an AI Worse at Writing GPU Code