Systemd supports the setup of real-time priority to services launched during the boot process. This is done using the following Directives in the Service section:
- CPUSchedulingPolicy=
Sets the CPU scheduling policy for executed processes. Takes one of other, batch, idle, fifo or rr. - CPUSchedulingPriority=
Sets the CPU scheduling priority for executed processes. The available priority range depends on the selected CPU scheduling policy. For real-time scheduling policies, an integer between 1 (lowest priority) and 99 (highest priority) can be used.
Example
This is the mcelog service unity:
[Unit] Description=Machine Check Exception Logging Daemon [Service] ExecStart=/usr/sbin/mcelog --ignorenodev --daemon --foreground [Install] WantedBy=multi-user.target
By adding the following directives in Service section:
CPUSchedulingPolicy=fifo CPUSchedulingPriority=20
For example:
[Unit] Description=Machine Check Exception Logging Daemon [Service] ExecStart=/usr/sbin/mcelog --ignorenodev --daemon --foreground CPUSchedulingPolicy=fifo CPUSchedulingPriority=20 [Install] WantedBy=multi-user.target
When restarted, the mcelog service will start with the priority set by systemd:
# tuna --show_threads | grep mcelog 4680 FIFO 20 0,1 2 0 mcelog
