I agree indeed. In statistical analysis or signal processing noise is described as an element presenting data/energy other than energy/data to be observed. I guess any data collecting system can call noise anything that is filtered out from that being measured.

It's about measuring jitter caused by the OS. When you have a large message passing system like you see in HPC environments, delays in processing exactly the right messages add up to huge failures of utilization because of the dependency graph of work to be done. In the past I had even seen national labs write their own Linux syscall compatible kernels in order to combat jitter. For example: https://github.com/HobbesOSR/kitten

It's about jitter caused by the OS, or in this case HW (e.g. due to SMM or similar shenanigans), that can be problematic for real time or HPC applications.