chrt:tldr:69d15

The command chrt --all-tasks --pid ${PID} is used to set or retrieve the scheduling policy and priority of a specified process with a given Process ID (PID).

Let's break down the command and its options:

• chrt is the command itself, which is used to manipulate process scheduling attributes.
• --all-tasks option is used to include all tasks (threads) of the specified process in the command's operation. By default, only the main thread of the process is considered.
• --pid ${PID} option specifies the Process ID (PID) of the process to be targeted. Here, ${PID} is a placeholder that needs to be replaced with an actual PID.

Depending on how the command is used, it can perform different tasks:

1. Retrieve the scheduling policy and priority:

   • When used without any additional options, the command will display the current scheduling policy and priority of the specified process.
   • For example, chrt --all-tasks --pid 1234 will show the scheduling policy and priority of the process with PID 1234.

2. Set the scheduling policy and priority:

   • By using the --sched-policy and --sched-priority options along with the command, you can set the scheduling policy and priority of the specified process.
   • For example, chrt --all-tasks --pid 1234 --sched-policy SCHED_FIFO --sched-priority 99 will set the scheduling policy of the process with PID 1234 to First-In-First-Out (SCHED_FIFO) and assign it a priority of 99.

Note: The available scheduling policies and priorities may vary depending on the system and kernel version.