I'd like a more systematic way for prioritizing my tasks with nice(1).
Obviously 0 is "normal", 19 is "lowest priority" and -19 is "highest priority", but what about all the other numbers?
If I have a job that is non-interactive (I'll go get coffee while it runs), I'd like to lower the priority a bit, but to which number? Should it be 1 or 2 or 10 or what?
Are there any "well-known" things that each priority number is used for?
The same questions apply to ionice.
nicepriority numbers only matter in relation to other processes. It's up to you to determine the structure you want and how much granularity you need. You can think of it as 3 for very low granularity or 5 groups for better granularity instead of the full range, e.g., High, Medium, Normal, Low, Really Low, and give those an arbitrary number value, say -19, -10, 0, 10, 19.The numbers in between can be used as needed when you have the one process that's a little more important than Medium Process X, but not as important as High Process Y. Chances are you won't need them, though.