Code-Memo

Process priorities (nice, renice)

Concepts

nice value: user-space hint to the scheduler (lower is higher priority)
Range usually -20 (highest priority) to 19 (lowest)
Only privileged users can set negative nice values

Start a command with a nice value

nice -n 10 tar -czf backup.tgz /data

Change priority of a running process

renice 15 -p 1234
renice -5 -p 1234           # requires privileges

Inspect process priorities

ps -o pid,ni,pri,cmd -p 1234
top                           # shows NI by default on many setups

Notes

CPU limits and IO limits are often better handled with cgroups (systemd)
Nice affects CPU scheduling, not memory usage

Signals and process control