Low latency Kernel

hdansin

Greetings,

As I use Solus for recording music, I was wondering if it would be possible to use/enable a low latency kernel. I've set up Jack, but I still notice enough latency to bother me when recording and monitoring with Ardour. I was reading about AVLinux and the Liquorix Kernel, and I believe Ubuntu Studio/Fedora Jam might do something with the Kernel to get lower latency. I am somewhat ignorant of what goes into installing different kernels, but it would be really great for creators to have a sort of AV Solus, if not an edition, at least the ability to get lower latency. If there's any way I could contribute to something like this, let me know.

qk4-li3

This is how to enable low-latency kernel in Solus:
Add 3 kernel parameters (preempt=full, threadirqs, mitigations=off) to a configuration file;

create directory sudo mkdir -p /etc/kernel/cmdline.d
create configuration file echo 'preempt=full threadirqs mitigations=off' | sudo tee /etc/kernel/cmdline.d/lowlatency.conf
apply these changes to clr-boot-manager sudo clr-boot-manager update

And reboot ...I think
PS. you can leave out mitigations=off, if you are concerned about spectre meltdown vulnerability. But there's possible CPU performance penalty with mitigations ON. My opinion, and how I set it, it's always OFF.

hdansin

qk4-li3 Thanks, I'll give this a try when I get some time.

BuzzPCSOS

Like @hdansin I made a note of this to try when I got some time.
The instructions supplied by @qk4-li3 worked fine but there did not seem to be much difference in performance after rebooting so I wanted to prove that I had made some sort of difference. I did not use the mitigations=off instruction.
Running uname -a returned the same output as before patching.
Linux dell-solus 6.16.5-322.current #1 SMP PREEMPT_DYNAMIC 2025-09-10 x86_64 GNU/Linux
Running dmesg | grep Preempt also returned the same output as before patching.
[ 0.103442] Dynamic Preempt: full [ 0.103483] rcu: Preemptible hierarchical RCU implementation.
Looking around on the net indicated that Preempt_Dynamic seems to be burnt into many distros so I guess this might be the same for Solus.
Disabling mitigations to security vulnerabilities could make a big difference to performance but I did not want to gamble with the security of my setup.
Does 'preempt=full threadirqs' actually make any noticeable difference? Or did I look in the wrong place to test it?
I would like to know to help me decide to keep these instructions written down or discard them.

Original-Syn

On an interesting note, Solus just switched to scx-sched from BORE. Which means now you can actually choose your scheduler

Snippet from last weeks announcement...

Our Linux kernel packages have been updated this week. Linux current is now at version 6.16.5, and our LTS kernel is at 6.12.45. More notably, our Linux current kernel is now using the scx-sched scheduler instead of BORE. This project is a collection of schedulers, so if the default scx_flash scheduler doesn't meet your needs, you can switch it out at runtime with the scxctl utility. The configuration file at /usr/share/defaults/scx_loader/config.toml contains instructions on how to change the scheduler permanently.

Some of the low-latency schedulers that I can think of are...
scx_lavd, scx_bpfland, and scx_flash (the one set by default now)

All of which can be configured to your needs better. Which is why I included the scx_flash that they set by default for Solus. Both scx_lavd and scx_bpfland have some good information out there for low latency as well.

BuzzPCSOS

Original-Syn Thank you for your quick reply. Wow, lots of options! I feel a little spoilt for choice now. Definitely will be doing a little reading before jumping in.

ibm450

so how do i know ive set it up correctly