[CentOS] low latency kernel?

[Lamar Owen]

On 04/02/2015 10:46 AM, Les Mikesell wrote:
> Someone recently posted on the x2go list that he had a problem with
> jerky videos playing remotely on Ubuntu, but solved it by installing a
> low latency kernel that was available as an alternative.  That made me
> curious as to whether CentOS has an equivalent - or a way to build
> something similar.
>
You want the kernel-rt package.  This is a part of the MRG packaging.  
The source RPM for the latest version for EL6 is at 
ftp://ftp.redhat.com/redhat/linux/enterprise/6Server/en/RHEMRG-RHEL6/SRPMS/kernel-rt-3.10.58-rt62.60.el6rt.src.rpm 
(and while looking in this area, I found some very interesting things in 
the 7 trees......).  I don't see a kernel-rt package in any of the C7 
repos, but sources are in the kernel-rt git at git.centos.org.  Just 
need to build it and its dependencies. Karanbir, Johnny, et al: are 
there any plans to build this at some point?

And then you'll want to read 
https://rt.wiki.kernel.org/index.php/RT_PREEMPT_HOWTO as the RT 
preemptable kernel has some differences in behaviors you need to be 
aware of.

I have used the RT_PREEMPT kernel, when dealing with multitrack audio 
setups where you need to do overdubbing and punchins/outs. Every 
millisecond counts when you have a musician or vocalist listening to a 
mix of 16 tracks, their own previously recorded track, and they need to 
punch in and perform (with pre-roll) a new take of a section then punch 
out to return to the previously recorded material.

Currently I use AVLinux for that task, but CentOS 7 plus the RT kernel 
(with all the tools needed for said kernel) would be fantastic; the 
software I use, Harrison Consoles' Mixbus (based on Ardour), runs very 
well on C7, but the latency is a bit too high (and far too 
nondeterministic thanks to clock scaling) for 16 channel overdubs with 
punchins/outs.  AVLinux works well for this.

Years ago, the way to get this on Red Hat Linux and later Fedora and 
CentOS was to install the kernel-rt from PlanetCCRMA; it's been a while 
since I looked for it there.  But Red Hat has the MRG product.