In the Linux environment, CPU scheduling plays a crucial role in optimizing system performance and resource allocation. The schedtool utility is a powerful tool that allows system administrators and developers to control and manipulate the CPU scheduler behavior. It provides a command-line interface to modify the scheduling parameters of a process, such as its priority, policy, and CPU affinity.

By using schedtool, you can fine-tune the CPU scheduling behavior to optimize the performance of critical processes, balance the workload across multiple CPUs, and prioritize specific tasks. This article will guide you through the usage of schedtool and demonstrate its importance in managing CPU scheduling in Linux.

Examples:

1. Installing schedtool: Before using schedtool, make sure it is installed on your Linux system. To install schedtool on Debian-based distributions, use the following command:

   sudo apt-get install schedtool

2. Setting the scheduling policy: You can use schedtool to set the scheduling policy of a process. The available policies are:

   • SCHED_OTHER: The default scheduling policy for most processes.
   • SCHED_FIFO: First-In-First-Out scheduling policy.
   • SCHED_RR: Round-Robin scheduling policy.

   To set the scheduling policy of a process with PID 1234 to SCHED_FIFO, use the following command:

   sudo schedtool -F -p 1 1234

3. Setting the scheduling priority: The scheduling priority determines the order in which processes are executed. A higher priority value means the process will be scheduled more frequently. The default priority is 0, and lower values represent higher priorities.

   To set the scheduling priority of a process with PID 1234 to -10, use the following command:

   sudo schedtool -n -10 1234

4. Setting the CPU affinity: CPU affinity determines which CPUs a process can run on. By setting the CPU affinity, you can control the allocation of CPU resources to specific processes.

   To set the CPU affinity of a process with PID 1234 to run only on CPU 0, use the following command:

   sudo schedtool -a 0 1234

   You can also specify multiple CPUs by separating them with commas. For example, to set the CPU affinity to CPUs 0, 1, and 2, use:

   sudo schedtool -a 0,1,2 1234