mo...@rodents-montreal.org (Mouse) writes: >> Modern hardware could easily do 100kHz.
>Not with curren^Wat least one moderately recent NetBSD version! >At work, I had occasion to run 9.1/amd64 with HZ=8000. This was to get >8-bit data pushed out a parallel port at 8kHz; I added special-case >hooks between the relevant driver and the clock (I forget whether >softclock or hardclock). It worked for its intended use fairly >nicely...but when I tried one of my SIGALRM testers on it, instead of >the 100Hz it asked for, I got signals at, IIRC, about 77Hz. Scheduling and switching userland processes is heavy. For a test try to schedule kernel callouts with high HZ values. That still generates lots of overhead with the current design but you should be able to go faster than 8kHz.
