Chapter 11. Setting the Scheduler
There are two different ways to configure and observe process configurations: the command line utilities, and the Tuna graphical tool. This section uses the command line tools, but all actions can also be performed using Tuna.
11.1. Using chrt
to Set the Scheduler
The
chrt
is used to check and adjust scheduler policies and priorities. It can start new processes with the desired properties, or change the properties of a running process.
To check the attributes of a particular process, use the
--pid
or -p
option alone to specify the process ID (PID):
~]#chrt -p 468
pid 468's current scheduling policy: SCHED_FIFO pid 468's current scheduling priority: 85 ~]#chrt -p 476
pid 476's current scheduling policy: SCHED_OTHER pid 476's current scheduling priority: 0
To set the scheduling policy of a process, use the appropriate command option:
Short option | Long option | Description |
---|---|---|
-f | --fifo | Set schedule to SCHED_FIFO |
-o | --other | Set schedule to SCHED_OTHER |
-r | --rr | Set schedule to SCHED_RR |
To set the priority of a process, specify the value before the PID of the process that is being changed. The following command will set the process with PID 1000 to
SCHED_FIFO
, with a priority of 50:
~]# chrt -f -p 50 1000
The following command will set the same process (PID 1000) to
SCHED_OTHER
, with a priority of 0:
~]# chrt -o -p 0 1000
To start a new application with a given policy and priority, specify the name of the application (and the path, if necessary) along with the attributes. The following command will start /bin/my-app, with a policy of
SCHED_FIFO
and a priority of 36:
~]# chrt -f 36 /bin/my-app
Note
For more information, or for further reading, the following man page is related to the information given in this section:
- chrt(1)