Photon Real-Time Operating System Command-line Interface
Photon Real-Time Operating System provides commands for manipulating real-time properties of processes.
tuna
The tuna utility can be used to view and modify process priorities, CPU isolation and other real time characteristics in the system.
Examples:
View processes and their RT scheduling policies and priorities: $ tuna -P
thread ctxt_switches
pid SCHED_rtpri affinity voluntary nonvoluntary cmd
1 OTHER 0 0 1211 917 systemd
2 OTHER 0 0 281 0 kthreadd
3 OTHER 0 0 3 1 rcu_gp
4 OTHER 0 0 2 1 rcu_par_gp
6 OTHER 0 0 8 1 kworker/0:0H-kblockd
13 FIFO 1 0 317 1 rcu_sched
16 FIFO 99 0 3 2 posixcputmr/0
17 FIFO 99 0 6 2 migration/0
679 FIFO 50 0 1647541 1 irq/58-eth0-rxt
The following tasks are performed by using the tuna command:
Isolate a set of CPUs
$ tuna -c <cpulist> -i (where <cpulist> can be X,Y-Z)See the list of processes running on the specific CPUs before and after isolation
$ tuna -c <cpulist> --show_threads $ tuna -c <cpulist> -i --show_threads
taskset
The taskset command can be used to get/set CPU affinity of tasks:
Run a program bound to a set of CPUs
$ taskset -c <cpulist> ./program (where <cpulist> can be X,Y-Z)Move a running task to a set of CPUs
$ taskset -c p <cpulist> <pid>View the CPU affinity settings of a running task
$ taskset -c -p <pid>
chrt
The chrt command can be used to get or set the real-time scheduling policies and priorities of processes:
- Modify the scheduling policy and priority of a running task
$ chrt -f -p <priority> <pid> (sets the task with pid
View the current scheduling policy and priority of a running task
$ chrt -p <pid>
ps
The ps command can be used to list processes with their scheduling policies and priorities:
$ ps -eo cmd,pid,cpu,pri,cls
`CMD ` ` PID CPU PRI CLS`
`/lib/systemd/systemd --swit ` ` 1 - 19 TS`
`[kthreadd]` ` 2 - 19 TS`