The chrt command is a utility in Linux that is used to set the real-time scheduling policy and priority of a process. Real-time scheduling is a type of scheduling algorithm that is used to give priority to certain processes and ensure that they are executed in a timely manner.
To use the chrt command, you will need to specify the priority level and scheduling policy that you want to set for a process. The priority levels range from -20 (highest priority) to 19 (lowest priority). The scheduling policies include SCHED_FIFO (first-in, first-out), SCHED_RR (round-robin), and SCHED_OTHER (normal scheduling).
For example, to set the priority level to -5 and the scheduling policy to SCHED_FIFO for the process with PID 12345, you can use the following command:
# chrt -f -p -5 12345
This will set the priority level to -5 and the scheduling policy to SCHED_FIFO for the process with PID 12345.
You can also use the chrt command with the -m option to display the current real-time scheduling policy and priority of a process:
# chrt -m 12345
This will display the current real-time scheduling policy and priority of the process with PID 12345.
If you encounter the below error while running the command chrt :
chrt: command not found
you may try installing the below package as per your choice of distribution:
| Distribution | Command |
|---|---|
| Debian | apt-get install util-linux |
| Ubuntu | apt-get install util-linux |
| Alpine | apk add util-linux |
| Arch Linux | pacman -S util-linux |
| Kali Linux | apt-get install util-linux |
| CentOS | yum install util-linux |
| Fedora | dnf install util-linux |
| OS X | brew install util-linux |
| Raspbian | apt-get install util-linux |
chrt Command Examples
1. Display attributes of a process:
# chrt --pid PID
2. Display attributes of all threads of a process:
# chrt --all-tasks --pid PID
3. Display the min/max priority values that can be used with `chrt`:
# chrt --max
4. Set the scheduling policy for a process:
# chrt --pid PID --deadline|idle|batch|rr|fifo|other
Conclusion
The chrt command is useful for fine-tuning the performance of real-time processes and ensuring that they are given the necessary resources to execute in a timely manner. It is also useful for setting the real-time scheduling policy and priority of processes that require a higher level of priority, such as audio or video playback applications.