GPU cache hit rate fluctuation problem

Ncu mainly uses the pmu units for statistics. Since the pmu units are limited, multiple replays are required to measure all the metrics. One can use serialization, clock frequency lock, and cache control during multiple runs to ensure reproducibility. I have asked a person from Nvidia on the forum before. He said that as long as the graphics card is not being used by others, the cache hit rate theoretically will not fluctuate. However, the cache hit rate we measured with ncu could differ from each other during the multi-times tests, which is not consistent with the answer above.
How can I explain this fluctuation in cache hits?
And, what does the “steady state” in the official document actually mean?