On Fri, 2017-08-18 at 11:54 +0200, Jaromír Mikeš wrote:
> irqbalance should be disabled?

"Disabling the irqbalance daemon
This daemon is enabled by default and periodically forces interrupts to
be handled by CPUs in an even, fair manner. However in realtime
deployments, applications are typically dedicated and bound to specific
CPUs, so the irqbalance daemon is not required." - https://access.redhat
.com/documentation/en-
US/Red_Hat_Enterprise_MRG/1.3/html/Realtime_Tuning_Guide/sect-
Realtime_Tuning_Guide-General_System_Tuning-
Interrupt_and_Process_Binding.html

> I have different output for rtirq status with kernel as one is only PREEMPT not RT
> Seems to be that rtirq need RT kernel to work fully.

No, as already pointed out, if you should use a kernel without the rt
patch, you need to add "threadirqs" to the boot options.

> /etc/init.d/rtirq status
>
>   PID CLS RTPRIO  NI PRI %CPU STAT COMMAND
>   424 FF      90   - 130  0.0 S    irq/31-snd_hda_
>   425 FF      85   - 125  6.0 S    irq/19-ehci_hcd
>   429 FF      85   - 125  0.1 S    irq/16-uhci_hcd
>   421 FF      84   - 124  0.0 S    irq/23-ehci_hcd
>   431 FF      84   - 124  0.0 S    irq/17-uhci_hcd
>   432 FF      83   - 123  0.0 S    irq/18-uhci_hcd
>   420 FF      82   - 122  0.0 S    irq/20-uhci_hcd
>   423 FF      81   - 121  0.0 S    irq/21-uhci_hcd
>    66 FF      80   - 120  0.0 S    irq/1-i8042
>   428 FF      80   - 120  0.0 S    irq/22-uhci_hcd
>    65 FF      79   - 119  0.0 S    irq/12-i8042
>    39 FF      50   -  90  0.0 S    irq/9-acpi
>    57 FF      50   -  90  0.0 S    irq/24-PCIe PME
>    58 FF      50   -  90  0.0 S    irq/25-PCIe PME
>    59 FF      50   -  90  0.0 S    irq/26-PCIe PME
>    60 FF      50   -  90  0.0 S    irq/27-PCIe PME
>    61 FF      50   -  90  0.0 S    irq/24-pciehp
>    62 FF      50   -  90  0.0 S    irq/25-pciehp
>    63 FF      50   -  90  0.0 S    irq/26-pciehp
>    64 FF      50   -  90  0.0 S    irq/27-pciehp
>    67 FF      50   -  90  0.0 S    irq/8-rtc0
>   105 FF      50   -  90  0.5 S    irq/14-ata_piix
>   106 FF      50   -  90  0.0 S    irq/15-ata_piix
>   408 FF      50   -  90  0.0 S    irq/28-mei_me
>   409 FF      50   -  90  0.0 S    irq/29-i915
>   418 FF      50   -  90  0.0 S    irq/17-rtl_pci
>   419 FF      50   -  90  0.0 S    irq/16-yenta
>   436 FF      50   -  90  0.0 S    irq/23-i801_smb
>   610 FF      50   -  90  0.0 S    irq/17-firewire
>   635 FF      50   -  90  0.0 S    irq/18-mmc0
>   640 FF      50   -  90  0.0 S    irq/18-r592
>   642 FF      50   -  90  0.0 S    irq/18-r852
>  1061 FF      50   -  90  0.0 S    irq/30-eth0
>   636 FF      49   -  89  0.0 S    irq/18-s-mmc0
>     3 TS       -   0  19  0.1 S    ksoftirqd/0
>    22 TS       -   0  19  0.1 S    ksoftirqd/1

You are giving snd_hda_ the highest prio. Don't do it. It much likely is
an onboard device you aren't using for real-time audio.

You are giving i8042 real-time priority, don't give keyboard and mouse
this priority.

Simply edit /etc/conf.d/rtirq RTIRQ_NAME_LIST to:

RTIRQ_NAME_LIST="usb"

After that don't restart rtirq, restart the computer.

irq/16, irq/23, irq/17 and irq/18 share IRQs, so consider to use the
ehci (USB2) port using IRQ 19. Avoid using uhci (USB1) or the ehci
(USB2) port hat shares the IRQ.