PRUs - not really deterministic, missing docs?

Hi, I have read an intro about PRUs “each PRU has its own single-cycle I/O

Well, nice. Let’s look further… "Content is no longer maintained and is being kept for reference only! " “has been set to read only” “this software package is no longer being maintained.”
Tried to send a message into BeagleBone PRU subforum… it happily disappeared forever.

But ok, it is just a possible warning. Let us look into the hard docs. a write instruction “executes in approximately 1 cycle” “Table 1 through Table 3 are considered “best-case” read latency values for the PRU”

Now it is not just a warning. It shows that the details of the “real-time” are some undocumented unknowns, and that these units might not be deterministic at all. “Might”, because there are just no precise docs and I am not going to reverse-engineer them. It would not give the real-time guaranties.

Possibly you could point me to some modern processing unit where there is at least a subset of instructions (including basic GPIO read/write and intercore communication) with precise execution times?

Please disregard, original thread is in the PRU subsection, posted here by mistake…