Change a Running Process's Priority with renice
Lower a process's scheduling priority without restarting it, so it stops starving everything else.
Run renice 10 -p 1234 to give the process the lowest standard priority; use a lower value like renice 5 -p 1234 to be gentler.
01Command
Command
$ renice <priority> -p <PID>02What it does
renice adjusts the nice value of a live process: higher nice numbers mean the scheduler favors it less, letting other work run smoothly while it grinds on. The -p flag says you are targeting a process ID. You can raise a process's own niceness freely, but lowering it (making the process more important) or renicing another user's process requires sudo.
03Risk
!Warning: Nice values only influence CPU scheduling, not disk or network I/O, so a reniced backup will still compete heavily for disk. Don't renice system-critical processes.
04Undo
Undo
$ renice 0 -p <PID>05Sources
- renice(1) man pageEvidence: The page documents renice priority -p pid for adjusting the nice value of running processes and the -p flag that interprets targets as process IDs.
- RENICE(8) — macOS man pageEvidence: The man page documents "-p Interpret target parameters as process ID's (the default)" and shows the example "renice +1 987 -u daemon root -p 32"; it notes only the super-user may alter other users' processes.
Last verified: 2026-09-19 · Category: System & Settings
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