[Fedora-music-list] Low Latency vs. Real Time Kernel - actual latencies ?

[Brian Monroe]

I think so too, thanks for chiming in.

I'm still waiting to get into the packagers group, but I have a koji
account and theoretically could compile an rt kernel. I think the standard
naming schema in other distros is kernel-rt. It should be only adding a few
lines to the spec file to enable the rt kernel, but when you look at how
many kernel update there are for Fedora every week, I'm not sure as to how
up to date we'll be able to keep up due to the work load. We're already are
down on developers, and people like Brandon are keeping us afloat.

Are we going to be ok as a project to be behind a week or two in Kernel
releases? Personally I'm for more stable kernels when it comes to music
production vs. having the latest and greatest, but I also think that should
be a clearly indicated as a feature

That being said, I feel strongly as though others should take this task on,
if not me, then someone else or better yet, a few of us.


I'm looking into the Ubuntu Studio and turns out they dropped the RT kernel
as default. They're using a "lowlatency" kernel instead of a rt kernel
(though they do still supply an rt kernel but not by default). I do know
that users are able to get 1.5 ms latency with zero xruns so I'm guessing
they're doing something other than real-time scheduling, I just don't know
what. Thoughts?

On Wed Nov 12 2014 at 10:40:44 AM Be Ing <be.0 at gmx.com> wrote:

> Hello Fedora musicians, I've been lurking this list for a little bit and
> this is my first time chiming in on something.
>
> I think it is important to pursue an official realtime kernel for Fedora.
> I think a distribution focused on audio without a realtime kernel would
> have a serious bug, that IMO, would be worth delaying publication for.
>
> >So I had a beer with hansomepirate(jdulaney), who is, or was on the kernel
> sig, last night and we got to talking about a RT kernel.
> >
> >Last time we talked to the kernel folks about an rt kernel, they weren't
> impressed with the "need" for Fedora, but that was before the Spin was
> officially out.
> >
> >Now might be a good time to raise this issue again? I dug through my
> archives and found this thread. Now that we have an actual spin that's out,
> we can actually redo some of the testing to have more realistic tests.
> (multitrack with effects)
> >
> >I feel like right now, it's one of the few benefits that the ubuntu studio
> folks have (or at least claim to have) over us. The other is some
> semi-proprietary software that on... you know what, never mind it's getting
> off topic.
> >
> >Anyways, does the list think this is worth pursuing?
> >
> >>On Wed Feb 22 2012 at 9:10:29 PM Brian Monroe <briancmonroe at gmail.com
> [https://admin.fedoraproject.org/mailman/listinfo/music]>
> wrote:
> >>
> >> Ok, I redid all the tests, while the system was only running my DE and
> the
> >> test, and then again when I put it under duress by running a script that
> >> looped "du -h /" and "ls -Ral /usr/" over and over. I ran the script
> twice
> >> to get my proc up a bit to emulate running some intese delays and
> reverbs
> >> or other effects.
> >>
> >> Ironically the kernels typically did better when the scripts were
> running.
> >> Personally I think there's a clear advantage with CCRMA's kernel or even
> >> just a preempt kernel in the max lat areas. Those max numbers jumped up
> >> close to where they were near the beggining of the test if anyone was
> >> wondering.
> >>
> >> Here's the file with both sets of tests and the uname -a info as
> requested
> >> by Fernando.
> >> -Brian
> >>
> >>> On Wed, Feb 22, 2012 at 6:54 AM, Brian Monroe <briancmonroe at
> gmail.com[https://admin.fedoraproject.org/mailman/listinfo/music]
> >>> wrote:
> >>> I'll be sure to include that on the next batch. I used the kernel you
> >>> after installing the CCRMA repo when you use yum install kernel-rt,
> which
> >>> happens to be 3.0.17-1.rt33.1.fc16.ccrma.x86_64.rt. I'll go back and
> >>> include the other info to the old results when I do the load testing
> >>> tonight or tomorrow.
> _______________________________________________
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> music at lists.fedoraproject.org
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