[linux-audio-user] kernel - using rtlimits, realtime_lsm

[Christoph Eckert]

> 1.  Build your own kernel from scratch - too complicated for me at
> this time

It's easy if you know what to do ;-) .

I made the experience that learning how to build a kernel still is 
useful these days, especially for audio stuff. Or using a well 
preconfigured audio distribution.

> 2.  Use the realtime_lsm module on an existing kernel - 
> I've tried this, but I read it's no longer supported in the kernel
> because of #3...

It's still supported and I run it on top of a recent 2.6.14.2 kernel. 
Advantage: it's realtively simple to build and use. Usually you do not 
need to rebuild a complete kernel, you only need to build that module 
and load it.

OTOH, the RT-LSM module "only" makes it possible that non-root users get 
access to realtime priviledges - it doesn't improve the latency of the 
system itself, so...

> 3.  Use rtlimits, which is already a part of the default kernel.

...this is the right thing to do, I guess.

> Last night I downloaded the set_rtlimits program and was able to get
> jackd running with real time capabilities.  I haven't done any
> real-world work yet, so I don't know if my efforts were truly
> successful.  Here are my questions:
>
> 1.  Is rtlimits all that I need for audio work?  It seems way too
> simple.  I remember that people using 2.4 kernels had at least two
> patches that had to be applied before the kernel was suitable for
> audio work.  If I use rtlimits, do I still need to build a kernel
> with, for instance, the ck patches for a preemptable kernel?

The default 2.6.14 kernel is much better for audio work than any kernel 
before. If it is good enough for your work, why bother yourself with 
kernel patching?

> 2.  Is anyone using rtlimits instead of realtime_lsm?  Is there any
> benefit to using one over the other, in terms of real-world audio
> work?
> 3.  Should I just break down and install DeMudi?  :)

DeMuDi and Planet CCRMA are known to work out of the box for audio work, 
that's what they are for ;-) .

> I hope my questions make sense.  Please feel free to correct any
> errors in my logic here, that is exactly what I am looking for - to
> learn how to do things myself the right way.

You're welcome.


Best regards


ce