Q: A batch processing job is consuming all available CPU, starving other services on the same server. How do you lower its CPU priority without killing it?

Linux uses a nice value (ranging from -20 to +19) to influence CPU scheduling priority. Higher nice values mean lower priority (the process is "nicer" to others).

• renice: renice +15 -p sets the process to a low priority, allowing other processes to get CPU time first.
• Starting with low priority: nice -n 15 ./batch_job.sh launches the process with reduced priority from the start.

To reduce priority of a running process: For stricter enforcement, use cgroups: This limits the process to 25% of a single CPU core regardless of system load—a hard cap rather than a scheduling hint. The difference: nice is a *soft* priority hint that only matters under contention. Cgroups provide a *hard* resource limit that is enforced regardless of whether other processes need CPU.

systemd-run --scope --property=CPUQuota=25% ./batch_job.sh