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.
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.
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Lamar Owen -
Les Mikesell