[ziggus]

I believe the question is less about input latency than (as mentioned,) scheduling latency or the amount of time from when the scheduler marks a process as 'ready to execute' to the time it actually starts executing.

SchedLat (https://tanelpoder.com/posts/schedlat-low-tech-script-for-me...) is one tool/approach to doing this, but it's a bit out of date.