Re: [LAU] rt-patch 23-Jul-2011

On Sun, 2011-07-24 at 18:59 +0200, Robin Gareus wrote:
> Hi Ralf,
>
> On Jul 24, 2011, at 4:12 AM, Ralf Mardorf wrote:
>
> > 3.0-rt2
> >
> > So, the "rt patch emulation" ex kernel 2.6.39 might be less good than a
> > kernel that is patched?
>
> It's not "emulation". A big part of the RT patch (e.g. threaded IRQ handlers) was been merged into 2.6.39.
> The goal of the Preempt-RT patch is to eventually end up completely in the vanilla (aka mainline) kernel.
>
> http://lwn.net/Articles/440064/ is a nice read on the current state of it.
>
> > Until now I build
> >
> > linux-image-2.6.33.9-rt31_2.6.33.9-rt31-10.00.Custom_amd64.deb
> > linux-image-2.6.39.1_2.6.39.1-10.00.Custom_amd64.deb
> >
> > but I only produced music with 2.6.33.9-rt31 until now, dunno if 2.6.39
> > isn't as good as a kernel-rt.
> >
> > Any information, experiences?
>
> I've been running 2.6.39 ever since it came out and used it for production. I can't tell a difference between it and the rt-patched 2.6.33 for general audio/video production. Neither will produce x-runs - unless I do sth stupid or overload the system.
>
> Threaded IRQ handling of the audio-interface and [high priority] FIFO scheduling are the important parts for low-latency audio and they're mainline in 2.6.39 (FIFO scheduling was for a long time already).
>
> There's a lot of small (but complex) things the RT patch does that are not in mainline yet (e.g pre-emptible memory-management, sleeping spinlocks) and can improve the guaranteed response-time of dedicated [audio] processes. However the gain [of code available in RT vs what is already mainline] is rather small when compared to latency requirements of audio (us vs. ms) and thus can be neglected on most systems. It'll probably give you an edge though.
>
> Long story short: If you just want to make music: stick with 2.6.39 or 3.0 - If you have the time and ability to debug: give 3.0-rt3 a go.
>
> Even though the impact of the RT-preemt patch on pro-audio is becoming less dramatic. It's a great project and important project.
>
> 2c,
> robin

Thank you for the explanation Robin :). Cheers! Ralf

_______________________________________________
Linux-audio-user mailing list
Linux-audio-user@email-addr-hidden
http://lists.linuxaudio.org/listinfo/linux-audio-user
Received on Sun Jul 24 20:15:03 2011