RestrictRealtime setting
The property RestrictRealtime is a systemd unit setting used for sandboxing. It is available since systemd 231.
Purpose: limit the ability to use realtime scheduling
Why and when to use RestrictRealtime
The setting RestrictRealtime aims to restrict the usage of realtime scheduling by a service.
When using this option enabled, a service won’t be able to use realtime scheduling policies, such as:
- SCHED_FIFO
- SCHED_RR
- SCHED_DEADLINE
- SCHED_OTHER / SCHED_NORMAL
Generic advice
This option can be applied to most services. Typically only a small amount of services that require priority scheduling should not be restricted.
To find out if any scheduling policy is used, considering looking in the code of the program or use the strings command.
Values
Systemd unit setting RestrictRealtime expects a boolean (yes/no or true/false).
| Value | Intended action | Available since systemd version |
|---|---|---|
| no | do not restrict a service - default | |
| yes | prevent service from using realtime scheduling |
Example to show the current value of RestrictRealtime for the ssh service:
systemctl show --property=RestrictRealtime ssh.serviceRelated hardening profiles
The systemd unit setting RestrictRealtime is used in the following hardening profiles.
