The config of the Ubuntu Studio Precise kernel 3.2.0-23-lowlatency, seems to be ready to use it with threadirqs as boot option. Anyway, I still get $ /etc/init.d/rtirq status PID CLS RTPRIO NI PRI %CPU STAT COMMAND 92 FF 90 - 130 0.0 S irq/8-rtc0 85 FF 85 - 125 0.0 S irq/18-ohci_hcd 89 FF 84 - 124 0.0 S irq/18-ohci_hcd 611 FF 83 - 123 0.0 S irq/18-snd_hdsp 1285 FF 82 - 122 0.8 S irq/18-nvidia 652 FF 80 - 120 0.0 S irq/20-snd_ice1 656 FF 80 - 120 0.0 S irq/21-snd_ice1 instead the of the wanted $ /etc/init.d/rtirq status PID CLS RTPRIO NI PRI %CPU STAT COMMAND 384 FF 90 - 130 0.0 S irq/8-rtc0 1102 FF 85 - 125 0.0 S irq/18-hdspm 1123 FF 80 - 120 0.0 S irq/20-ICE1712 1135 FF 80 - 120 0.0 S irq/21-ICE1712 So for the moment I guess it's better instead of using $ grep RTIRQ_NAME_LIST /etc/default/rtirq RTIRQ_NAME_LIST="rtc hdspm snd usb i8042" which does the trick for other installs, to use $ grep RTIRQ_NAME_LIST /etc/default/rtirq RTIRQ_NAME_LIST="rtc snd usb i8042" since this results in $ /etc/init.d/rtirq status PID CLS RTPRIO NI PRI %CPU STAT COMMAND 92 FF 90 - 130 0.0 S irq/8-rtc0 702 FF 85 - 125 0.0 S irq/20-snd_ice1 724 FF 85 - 125 0.0 S irq/21-snd_ice1 717 FF 83 - 123 0.0 S irq/18-snd_hdsp 1348 FF 82 - 122 0.8 S irq/18-nvidia 78 FF 80 - 120 0.0 S irq/19-ehci_hcd 80 FF 80 - 120 0.3 S irq/16-ohci_hcd 82 FF 79 - 119 0.0 S irq/17-ohci_hcd 84 FF 78 - 118 0.0 S irq/18-ohci_hcd 87 FF 78 - 118 0.0 S irq/17-ohci_hcd 89 FF 77 - 117 0.0 S irq/18-ohci_hcd 91 FF 75 - 115 0.0 S irq/1-i8042 20 FF 50 - 90 0.0 S irq/9-acpi 67 FF 50 - 90 0.2 S irq/22-ahci 279 FF 50 - 90 0.0 S irq/14-pata_ati 280 FF 50 - 90 0.0 S irq/15-pata_ati 292 FF 50 - 90 0.0 S irq/22-firewire 561 FF 50 - 90 0.0 S irq/7-parport0 1020 FF 50 - 90 0.0 S irq/43-eth0 3 TS - 0 19 0.2 S ksoftirqd/0 9 TS - 0 19 0.2 S ksoftirqd/1 so my MIDI interfaces snd_ice1... get a higher priority than the audio card snd_hdsp..., but at least all the other stuff get a lower priority. On other installs I also got/get the wanted priority for a non-rt, with threadirqs, e.g.: spinymouse@avlinux:~$ uname -a Linux avlinux 3.0.23-avl-7-pae #28 SMP PREEMPT Thu Mar 1 19:14:14 EST 2012 i686 GNU/Linux spinymouse@avlinux:~$ /etc/init.d/rtirq status PID CLS RTPRIO NI PRI %CPU STAT COMMAND 452 FF 90 - 130 0.0 S irq/8-rtc0 1028 FF 85 - 125 0.0 S irq/18-hdspm 1040 FF 80 - 120 0.0 S irq/20-ICE1712 1042 FF 80 - 120 0.0 S irq/21-ICE1712 615 FF 75 - 115 0.0 S irq/19-ehci_hcd 620 FF 75 - 115 0.2 S irq/16-ohci_hcd 622 FF 74 - 114 0.0 S irq/17-ohci_hcd 626 FF 73 - 113 0.0 S irq/17-ohci_hcd 445 FF 70 - 110 0.0 S irq/1-i8042 96 FF 50 - 90 0.0 S irq/9-acpi 621 FF 50 - 90 0.1 S irq/22-firewire 625 FF 50 - 90 0.0 S irq/18-ohci_hcd 627 FF 50 - 90 0.0 S irq/18-ohci_hcd 628 FF 50 - 90 0.0 S irq/14-pata_ati 629 FF 50 - 90 0.0 S irq/15-pata_ati 634 FF 50 - 90 0.3 S irq/22-ahci 909 FF 50 - 90 0.0 S irq/7-parport0 1414 FF 50 - 90 0.0 S irq/43-eth0 3 TS - 0 19 0.0 S ksoftirqd/0 9 TS - 0 19 0.0 S ksoftirqd/1 Could it be the kernel version or video driver? Any hints are welcome, Ralf PS: I did not test if it really does matter if the audio card has a higher or lower priority than the MIDI cards.