Hi, the machine was up for 19 days, hence in the meantime systemd was updated. Today I build 5.15.73.52.realtime1-1-rt-lts from AUR as provided by David, IOW without any changes done by me, but I didn't build in a clean chroot. Bevor that I run my own package of linux-rt 4.19.246_rt110-0.1000 without doing anything special to it, just CONFIG_AUDIT was disabled. Since last startup rtirq was updated, too, but the only changes were migrations from egrep to grep -E. In the past it happened very, very, very ... very seldom that after startup the PCI or PCIe card didn't get a high priority, which always was fixed by a single reboot. Today, when booting 5.15.73.52.realtime1-1-rt-lts 4 times, the first time snd_ice1 didn't get a high priority and the other times snd_ice1 as well as snd_hdsp didn't get a high priority. I doubt that it's related to the kernel. I suspect a systemd related race condition, but I might be completely mistaken. Any pointers are welcome. Regards, Ralf [rocketmouse@archlinux ~]$ grep RTIRQ_NAME_LIST..u /etc/rtirq.conf RTIRQ_NAME_LIST="usb snd_hdsp snd_ice1" [rocketmouse@archlinux ~]$ rtirq status PID CLS RTPRIO NI PRI %CPU STAT COMMAND 124 FF 90 - 130 0.0 S irq/16-ehci_hcd 184 FF 90 - 130 0.0 S irq/31-xhci_hcd 128 FF 89 - 129 0.0 S irq/23-ehci_hcd 88 FF 50 - 90 0.0 S irq/9-acpi 102 FF 50 - 90 0.0 S irq/29-ahci[000 116 FF 50 - 90 0.0 S irq/30-ahci[000 130 FF 50 - 90 0.0 S irq/8-rtc0 183 FF 50 - 90 0.0 S irq/1-i8042 324 FF 50 - 90 0.0 S irq/5-parport0 403 FF 50 - 90 0.0 S irq/32-mei_me 506 FF 50 - 90 0.0 S irq/18-i801_smb 572 FF 50 - 90 0.0 S irq/16-snd_hdsp 604 FF 50 - 90 0.0 S irq/34-i915 641 FF 50 - 90 0.0 S irq/35-snd_hda_ 644 FF 50 - 90 0.0 S irq/16-snd_ice1 16 TS - 0 19 0.0 S ksoftirqd/0 30 TS - 0 19 0.0 S ksoftirqd/1 [rocketmouse@archlinux ~]$ uname -rm 5.15.73.52.realtime1-1-rt-lts x86_64 [rocketmouse@archlinux ~]$ pacman -Q linux-rt linux-rt 4.19.246_rt110-0.1000 [rocketmouse@archlinux ~]$ pacman -Q rtirq rtirq 20220923-1 [rocketmouse@archlinux ~]$ pacman -Q systemd systemd 251.6-1 [root@archlinux rocketmouse]# rtirq stop Setting IRQ priorities: stop [ehci.hcd] irq=16 pid=124 pid=124 prio=50: OK. Setting IRQ priorities: stop [ehci.hcd] irq=23 pid=128 pid=128 prio=50: OK. Setting IRQ priorities: stop [xhci.hcd] irq=31 pid=184 pid=184 prio=50: OK. [root@archlinux rocketmouse]# rtirq start Setting IRQ priorities: start [ehci.hcd] irq=16 pid=124 prio=90: OK. Setting IRQ priorities: start [ehci.hcd] irq=23 pid=128 prio=89: OK. Setting IRQ priorities: start [xhci.hcd] irq=31 pid=184 prio=90: OK. Setting IRQ priorities: start [snd_hdsp] irq=16 pid=572 prio=85: OK. Setting IRQ priorities: start [snd_ice1] irq=16 pid=644 prio=80: OK. [root@archlinux rocketmouse]# rtirq status PID CLS RTPRIO NI PRI %CPU STAT COMMAND 124 FF 90 - 130 0.0 S irq/16-ehci_hcd 184 FF 90 - 130 0.0 S irq/31-xhci_hcd 128 FF 89 - 129 0.0 S irq/23-ehci_hcd 572 FF 85 - 125 0.0 S irq/16-snd_hdsp 644 FF 80 - 120 0.0 S irq/16-snd_ice1 88 FF 50 - 90 0.0 S irq/9-acpi 102 FF 50 - 90 0.0 S irq/29-ahci[000 116 FF 50 - 90 0.0 S irq/30-ahci[000 130 FF 50 - 90 0.0 S irq/8-rtc0 183 FF 50 - 90 0.0 S irq/1-i8042 324 FF 50 - 90 0.0 S irq/5-parport0 403 FF 50 - 90 0.0 S irq/32-mei_me 506 FF 50 - 90 0.0 S irq/18-i801_smb 604 FF 50 - 90 0.0 S irq/34-i915 641 FF 50 - 90 0.0 S irq/35-snd_hda_ 16 TS - 0 19 0.1 S ksoftirqd/0 30 TS - 0 19 0.1 S ksoftirqd/1