[LAU] Basic question about use of a lowlatency kernel

[Ralf Mardorf]

On Mon, 18 Feb 2013 23:59:30 +0100, Len Ovens <len at ovenwerks.net> wrote:
> On Mon, February 18, 2013 12:36 pm, jonetsu at teksavvy.com wrote:
>> If a better response time from the kernel is something that's Good, why
>> isn't lowlatency kernels a default in Linux distros (well, at least in
>> Linux Mint and Fedora)  If it is So Good, what are the arguments for not
>> having a lowlatency kernel by default ?  Any drawbacks ?  I presume the
>> Audio-oriented Linux distros do have lowlatency kernels by default, do
>> they ?
>
> low latency does not equal performance.
> low latency and high throughput are not the same either.
>
> Low latency means servicing an audio device more often, complete with the
> overhead involved in that. It means prioritizing one set of RT/lowlatency
> processes over others for a set purpose. when running audio at a low
> latency, the rest of my desktop slows down a lot to make sure my audio
> does not glitch.
>
> Low latency is a different set of priorities than performance.

Performance for _my_ averaged non-audio desktop usage isn't less good,  
when using a kernel-rt or full preempt kernel with threadirqs set, than  
when using a vanilla or so called desktop optimized kernel, so I'm usually  
using a self compiled kernel-rt. However, I'm seldom toying around with my  
computer, so "averaged non-audio" does mean that I use mail clients,  
browsers and GIMP, even for consuming multimedia, I seldom use the  
computer.

But making the kernel-rt a default, would be as bad, as making flashy  
animated 3D desktops a default, so IMO distros should stop this desktop  
insanity, but keep non-rt-kernels, while providing a kernel-rt by the  
repositories.

2 Cents,
Ralf