Problems starting in realtime mode

By default, Jack starts up in realtime mode. If the user starting jack is not allowed to start realtime processes, the following error might occur:

cannot use real-time scheduling (FIFO at priority 10) [for thread -1210562896, from thread -1210562896] (1: Operation not permitted)

In this case, you might want to set up your limits.conf to allow the audio group access to realtime priorities as documented at http://wiki.linuxmusicians.com/doku.php?id=system_configuration#limits.conf .