# Jack real-time audio



## Grenouille (Oct 28, 2016)

Hello,

I want to run jack (for use with zynaddsubfx), but it doesn't launch, telling real-time scheduling is not permitted :


```
JACK compiled with System V SHM support.
cannot use real-time scheduling (FIFO at priority 10) [for thread 25255936, from thread 25255936] (1: Operation not permitted)
cannot create engine
connect(2) call to /tmp/jack-1001/default/jack_0 failed (err=No such file or directory)
connect(2) call to /tmp/jack-1001/default/jack_0 failed (err=No such file or directory)
connect(2) call to /tmp/jack-1001/default/jack_0 failed (err=No such file or directory)
connect(2) call to /tmp/jack-1001/default/jack_0 failed (err=No such file or directory)
connect(2) call to /tmp/jack-1001/default/jack_0 failed (err=No such file or directory)
attempt to connect to server failed
Error, failed to open jack client on server:  status 17
Error, NULL jackClient through Start()
ERROR: The default audio output failed to open!
```

How can I allow this so jack can work ?

Thank you.


----------



## marcelbonnet (Oct 28, 2016)

You cannot use realtime as normal user.

As normal user, launch jackd as `jackd -r ... other args` for no realtime.

But, if you want realtime, you may run jackd as root (a don't do that), or ask root to give you realtime priority for jack (a do that):

`# rtprio 0 -`pgrep -o jackd``

The `pgrep -o jackd`  is an example. Make sure you know its pid.


----------

