The different realtime kernels

[Ralf Mardorf]

On Thu, 2010-09-30 at 07:35 -0400, Ronan Jouchet wrote:
> Hello everybody,
> 
> Many are confused about the various realtime kernels, so here is a 
> reminder of the situation as of Sept. 2010 (but _please_ see 
> https://help.ubuntu.com/community/UbuntuStudio/RealTimeKernel , which is 
> more detailed and continuously updated).
> 
> ***Summary***
> vanilla = unpatched kernel straight from kernel.org
> generic = vanilla + ubuntu sauce (it's the default ubuntu kernel)
> 
> The *soft realtime kernels, prepared by changing build-time parameters*
>      preempt = generic + mild configuration to reduce latency
>      lowlatency = generic + aggressive configuration to reduce latency
> 
> The *hard realtime kernels, prepared by applying a big patch* from Ingo 
> Molnar to the kernel source before building:
>      realtime = vanilla + patch (hard to maintain and stabilize because 
> merging 2 pieces of code is never easy)
>      rt = generic + patch (even harder to maintain and stabilize because 
> merging 3 pieces of code is harder than 2)
> 
> ***Availability***
> - for Maverick, generic will be the only kernel in the archives, thus 
> the default kernel for ubuntu and ubuntustudio, but Alessio has been 
> maintaining a PPA providing lowlatency and realtime
> - for Natty or later: work is being done to include lowlatency in the 
> official archives and make it the default ubuntustudio kernel
> 
> I hope this clears some doubts. By the way, this confusion is only going 
> to get more intense at release time (less informed / technical users). 
> Could we include some kind of note informing users about this? Why not a 
> "RealTime kernel help" item in the Audio Production menu, redirecting to 
> the wiki page?
> 
> Good day,
> 
> -- Ronan Jouchet

For what do multimedia users (producers, but consumers) need more, but
vanilla + rt-patch? Does somebody run a multi-user data server on the
same machine, as he is using in his audio or audio-video studio? This
would be nonsense.

2 cents,
Ralf