Using Ubuntu low latency & real time kernels

[Snoopy8]

Ubuntu 24.04 comes with both low latency and real time kernels, potentially improving SQ.

Suggest adding an option within SnakeOil tab to set the low latency kernel to full preempt.
https://discourse.ubuntu.com/t/fine-tuni...ency/44834
Another option is to enable nohz_full for the CPU's dedicated to the music players using CPUset. 

The real time kernel is available for both AMD and ARM processors.
https://ubuntu.com/real-time
Have a SO option to simplify the process to login to Ubuntu Pro and get the Real time kernel. 

Just in case people are not aware, Ubuntu Pro is free and the RT kernel can be downloaded free for use on 5 instances.

[Snoopy8]

Had an initial look at the tweaking options and they are not compatible with CPUset, and less friendly. 

My CPUset journey has been posted here
https://www.snakeoil-os.net/forums/Threa...-processes
https://www.snakeoil-os.net/forums/Threa...untu-22-04
However, I have come back to using the SO simple  version. Perhaps it is time to drop CPUset? 

Using pre-empt=full, nohz_full on CPUs dedicated to the music player and proper IRQ affinity settings (dedicate a CPU for the music output IRQ, shift other IRQS to other CPUs ) could potentially make SO sound even better.   Ideally, SO should hide the complexity of setting this up, providing options to: 

• enable RT kernel (using Ubuntu Pro)
  
• Dedicate CPU(s) to music player
  

[Snoopy8]

Just a note for those trying to install the Ubuntu real time kernel yourself.  I just used this on my Pi5.

1. Login to Ubuntu Pro, and go "Your Subscriptions" tab
   
2. In free personal token, copy the command "sudo pro attach xxxxxx" where xxxxx is a token
   
3. On Pi5/Pi4, run the above command
   
4. Then run "sudo pro enable realtime-kernel --variant=raspi"
   
5. Reboot
   

In SnakeOil/Linux Kernel tab, you should see the real time kernel and can swap back to original kernel.

[agent_kith]

This will hopefully come in 1.4.2.... I've spent the past few days working on re-working the Snakeoil API server and it's really a lot more work than anticipated (and only 30% done). 
Good thing is when completed it will be even easier to add new features like this.



This means 116 files have been modified. Of which 10,610 lines have been added, wihel 4372 have been removed

[wxrbbs]

[font]Had an initial look at the tweaking options and they are not compatible with CPUset, and less friendly. 

My CPUset journey has been posted here
https://www.snakeoil-os.net/forums/Threa...-processes
https://www.snakeoil-os.net/forums/Threa...untu-22-04
However, I have come back to using the SO simple  version. Perhaps it is time to drop CPUset? 

Using pre-empt=full, nohz_full on CPUs dedicated to the music player and proper IRQ affinity settings (dedicate a CPU for the music output IRQ, shift other IRQS to other CPUs ) could potentially make SO sound even better.   Ideally, SO should hide the complexity of setting this up, providing options to: [/font]

• enable RT kernel (using Ubuntu Pro)
  
• Dedicate CPU(s) to music player
  

[font]Hello, it seems that switching kernels in the new version 1.4 still doesn't work, and it requires manual command operations to achieve it.[/font]

[Snoopy8]

Hello, it seems that switching kernels in the new version 1.4 still doesn't work, and it requires manual command operations to achieve it.

Is this for the Pi or AMD?  I have used both the Ubuntu and my own RT kernel and successfully changed them within SO 1.4.

[wxrbbs]

Hello, it seems that switching kernels in the new version 1.4 still doesn't work, and it requires manual command operations to achieve it.

[font]Is this for the Pi or AMD?  I have used both the Ubuntu and my own RT kernel and successfully changed them within SO 1.4.[/font]

pi cm4

[Snoopy8]

pi cm4

Thank you for identifying this problem for AK's issues list. Confirming that SO is unable to change the kernel for both CM4 and Pi5.

In Amd version, SO can change kernel.

[wxrbbs]

pi cm4

Thank you for identifying this problem for AK's issues list. Confirming that SO is unable to change the kernel for both CM4 and Pi5.

In Amd version, SO can change kernel.

en nice work，in pi cm4 is /boot/firmware，not GRUB !!! 

so @agent_kith  fix it 

[agent_kith]

so @[/color]agent_kith  fix it [/b][/size]

It's in the works. Until then, you can always switch the kernel outside the WebApp. As much as as I would love to get everything done, there's a huge backlog of work to catch up..

Look at the this work that I'm currently working on (Link): 135 files modified, 11290 lines added, 7194 lines remove. And it's only about 50-65% complete

Realistically it will be a while before I can get working on this. Of course I will be motivated to focus on this earlier if I find a good Pi 5 board that gives out excellent sound quality. But yet to know of one. Until then I had to pick the battles I can fight.