[split] Real Time Kernels discussion

[agent_kith]

FYI, from UbuntuStudio/RealTimeKernel - Community Help Wiki  Maybe we can simply focus on UbuntuStudio 22.04. 

About RealTime KernelsEarly on in Linux audio production, Real-Time kernels were the only way to get low- and no-latency audio for professional audio applications. However, since Linux 2.6, the real-time stack has been part of the Linux kernel, having a kernel patched with a real-time stack is no longer necessary.
 
RealTime Kernels Still ExistHowever, there continued to be a demand for real-time kernels with a special patch. A patch does exist to enable process to have real-time process access to any process requesting it. This is good for applicance-like applications, such as audio mixers that use Linux (the Behringer X-series mixers and the Allen & Heath iLive series mixers are good examples). For desktop computer use, THIS IS A BAD IDEA.

They are not wrong. It is a bad idea, for desktop (i.e. general use).

I guess I should put up a clarification in the wiki for this. That Snakeoil is a dedicated music server/player. And should not be used for general computing (e.g. use it to browse banks, install pirated applications, etc).

Low-Latency KernelThe Low-Latency Kernel included in Ubuntu Studio (and available in the Ubuntu repositories) does not allow such malicious code from locking-out a user from their machine. It does contain other optimizations, such as Preempt-RT being enabled in the kernel configuration, to achieve the lowest possible latency for audio and other applications, while keeping the user interface usable. Latency as low as 0.1 millisecond can and has been achieved using this kernel.
 
SummaryFor desktop computer usage, using a real-time kernel can cause security nightmares. The low-latency kernel included in Ubuntu Studio is completely capable of low- to no- latency while not enabling malicious processes to lock-out a user from their computer.

This is the interesting bit... I havn't look at the code for a wihle now, but if memory serves for real "Real time" (RT), Preempt-RT scheduling needs the process to be running as ROOT. Sounds like they have applied modifications to it that doesn't require that. I suspect it wouldn't be true real time, but it might be good enough.

Hopefully can get to try studio soon. Been somewhat busy lately.