[LAU] reducing xruns (System configuration)

[Ralf Mardorf]

On Thu, 19 Jul 2018 20:25:42 -1000, david wrote:
>4.8 doesn't have the Spectre/Meltdown patches. 4.16 does. So I blame
>the Spectre/Meltdown patches.

I already pointed tis out by an earlier mail:

"I didn't test, if the page table isolation stuff has got impact on
real-time performance, maybe you want to disable it, if so add 'nopti':

[rocketmouse at archlinux ~]$ grep -A3
'\^nopti' /boot/syslinux/syslinux.cfg MENU LABEL Arch Linux threadirqs
^nopti LINUX ../vmlinuz-linux
    APPEND root=LABEL=archlinux ro threadirqs nopti
    INITRD ../intel-ucode.img,../initramfs-linux.img" - 

https://lists.linuxaudio.org/archives/linux-audio-user/2018-July/110576.html

By the kernel package's changelog you could see if 'nopti' is
available. For older official Ubuntu kernels is was 'nokaiser', but for
all current official Ubuntu kernels it is 'nopti'.

The output of

ls -hAl /sys/devices/system/cpu/vulnerabilities/; cat /sys/devices/system/cpu/vulnerabilities/*

shows if PTI mitigation is enabled at all.