Do I really need an RT(Real Time) kernel

What other apps and distros do you use to round out your studio?

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brummer

Re: Do I really need an RT(Real Time) kernel

Post by brummer »

raboof wrote: However, AFAIK their target audience isn't really the pro audio crowd. I think they actually are doing it for controling laser beams, other machinery and stock exchanges.
Right, the current maintainer of the rt-kernel team is Thomas Gleixner, he is also the Manager of the Linutronix company, witch provide linux based solutions for industries.
So latest development of the rt-patch have more the needs from industrial devices in mind, but that didn't mean that linux pro audio don't benefit from it any more.

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raboof
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Re: Do I really need an RT(Real Time) kernel

Post by raboof »

brummer wrote:
raboof wrote:However, AFAIK their target audience isn't really the pro audio crowd. I think they actually are doing it for controling laser beams, other machinery and stock exchanges.
Right, the current maintainer of the rt-kernel team is Thomas Gleixner, he is also the Manager of the Linutronix company, witch provide linux based solutions for industries. So latest development of the rt-patch have more the needs from industrial devices in mind, but that didn't mean that linux pro audio don't benefit from it any more.
Agreed entirely.

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Re: Do I really need an RT(Real Time) kernel

Post by slowpick »

raboof wrote: However, AFAIK their target audience isn't really the pro audio crowd. I think they actually are doing it for controling laser beams, other machinery and stock exchanges.
Thats a bit of an awkward statement. They can't really 'target' pro audio, because only
a tiny faction of pro audio people use linux, let alone use it with exclusivity.

Having an RT linux studio distro, at least counters one of several initial concerns,
a curious pro will have: 'Will it be fast enough?'. Others being, what hardware do I need, where are the apps, what things are impossible, what things can I do easier, better, faster,
and not to be discounted, will I have more fun etc etc

Nearly all my hard and software works in linux, I don't do huge track-count productions,
the easier better faster questions, my own version of slowness negates, and I have
much more fun, working in linux. :)

brummer

Re: Do I really need an RT(Real Time) kernel

Post by brummer »

slowpick wrote:
raboof wrote: However, AFAIK their target audience isn't really the pro audio crowd. I think they actually are doing it for controling laser beams, other machinery and stock exchanges.
Thats a bit of an awkward statement. They can't really 'target' pro audio, because only
a tiny faction of pro audio people use linux, let alone use it with exclusivity.
That is a awkward statement, because that:
l0wt3ch wrote:Another thing to consider is: why does the rt-kernel team continue to put work into making patches, if there's no use doing it with newer kernels? I'll give you a hint: it's not for controlling laser beams.

Does anyone really think Ingo Molnar and the other developers just like wasting their time for no reason?
is simply wrong, raboof corrected it with his statement.
Also, that:
l0wt3ch wrote:The main goal in audio-processing is the latency
is simply wrong. True, we wont the lowest possible latency, but the main goal is a stable time frame, to avoid glitches.
Fortunately the needs of the industries covered the needs of audio production in this case, so linux audio benefit from the rt patch set.

Thad E Ginathom
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Re: Do I really need an RT(Real Time) kernel

Post by Thad E Ginathom »

True, we wont the lowest possible latency, but the main goal is a stable time frame, to avoid glitches.
Exactly. It doesn't matter how fast the cars are, if they are stopped at the signal to let something else pass. Interrupts are the signals

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Re: Do I really need an RT(Real Time) kernel

Post by slowpick »

brummer wrote:True, we wont the lowest possible latency, but the main goal is a stable time frame, to avoid glitches.
Fortunately the needs of the industries covered the needs of audio production in this case, so linux audio benefit from the rt patch set.
Using various RT kernels for years, I don't get enough glitches to worry about. Most of those few,
are from abuse of modulations, and then, the harsh reality that
keyboard/guitar blunders do transcend all those by far.

Corporations provide a foundation of an improving linux kernel, that benefits linux audio,
but distro coders do the covering, and app coders provide the needed content.

So, in the same breath, thanks go to both IBM and brummer, nVidia and lowtech,
Intel and falk, Red Hat and gmac, etc etc etc :)

brummer

Re: Do I really need an RT(Real Time) kernel

Post by brummer »

slowpick wrote: Corporations provide a foundation of an improving linux kernel, that benefits linux audio,
but distro coders do the covering, and app coders provide the needed content.

So, in the same breath, thanks go to both IBM and brummer, nVidia and lowtech,
Intel and falk, Red Hat and gmac, etc etc etc :)
You can thank whom ever you like, but note please that others have a other opinion over that.
In particular, your second pair, brings this video in my mind. :wink:
http://www.youtube.com/watch?v=paucVGmL ... re=related

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Re: Do I really need an RT(Real Time) kernel

Post by l0wt3ch »

I emailed the realtime kernel team directly, and was waiting for their response. I asked Thomas Gleixner:
Is it true that with irq handling being in the mainline kernel now, that the realtime kernel is mainly for industrial purposes?
He replied:
Threaded irqs are helping, but they still do not provide real-time guarantees. The RT patch is still developed and slowly integrated into the mainline to provide a full deterministic behaviour.
As for the realtime kernel's "target market", Gleixner insists "We have no primary audience" and that "professional audio has been a steady consumer of RT in the last years".

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Re: Do I really need an RT(Real Time) kernel

Post by l0wt3ch »

My quote from proaudio.tuxfamily.org on the previous page was intended to illustrate the difference between the stock Linux kernel and the latencies of a Mac, and to ask the question: "Why settle when you can have the best?"

I would guess that even some of my opponents understand the value of a realtime kernel. Otherwise, why statements like this:
True, we wont [sic] the lowest possible latency, but the main goal is a stable time frame, to avoid glitches. Fortunately the needs of the industries covered the needs of audio production in this case, so linux audio benefit from the rt patch set.
By the way, I've had success with kernels that were just low-latency on my set-up in the past. I even recorded an entire album this way. But you know what I wished for the whole time? A real-time kernel.

Because why settle for second best? :D

brummer

Re: Do I really need an RT(Real Time) kernel

Post by brummer »

Otherwise, why statements like this:
Because you try to imply wrong conclusions. Therefore here is no need. We need no pseudo magical talk.
I'm a subscriber to the rt-kernel list for several years now. I use rt-kernels only since version 2.16.4.
I always use plain vanilla +rt-patch kernels and use right now Kernel 3.4.1-rt9
So I know very well were I talk about.

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Re: Do I really need an RT(Real Time) kernel

Post by l0wt3ch »

brummer wrote:Because you try to imply wrong conclusions. Therefore here is no need. We need no pseudo magical talk. I'm a subscriber to the rt-kernel list for several years now. I use rt-kernels only since version 2.16.4. I always use plain vanilla +rt-patch kernels and use right now Kernel 3.4.1-rt9. So I know very well were I talk about.
B-but... but... I thought that lowlatency kernels were just as good, and that was why the other distro maintainers who frequent this site use them?? I mean, they wouldn't sacrifice the best choice for pro audio work just for the closed-source Nvidia drivers, would they? :roll: (And they wouldn't use KDE just because they liked it, whether or not it sucks compared to lightweight desktop environments, etc, etc...)

Could you enlighten me, Mr. Brummer, as to what you mean by "pseudo magical talk"?

And where were you earlier in the thread, when the world could have benefitted from your wisdom regarding the superiority of realtime kernels?

Thank you.

l0wt3ch
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Re: Do I really need an RT(Real Time) kernel

Post by l0wt3ch »

After I thanked him for his time, Thomas Gleixner sent me another email. (What a gentleman! I wish more people in Linux audio were as nice.) As an afterthought, he said:
It's definitely the best choice for audio production, if you want to make sure that you won't miss a sample. That's especially true for live mixing, when you definitely want to make sure that no high pitch distortion reaches a 50kW amp/speaker combo.

Again, we know about the audio requirements, but they are not that different from other use cases of RT. It all boils down to not missing the deadline.
So they are aware of our needs in the Linux audio world, it's just that all use cases of RT are similar...

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Re: Do I really need an RT(Real Time) kernel

Post by GMaq »

Hi,

FWIW we provide low-latency kernels for AV Linux however our kernel dev now has a testing repo with the latest 3.4 series RT's. So far the feedback on the rt's has been quite poor as far as reliability, unexpected x-runs and shutdown issues are concerned and a very telling fact is that we have surprising relatively little interest in the -RT's because our users are content with the performance and stability of the low-latency defaults and yes a majority of them want closed-source Video drivers as well. Focusing completely on one very misunderstood aspect of the complete multimedia desktop (latency) is not really a wise approach to the best user experience IMHO. Latency needs to 'low enough' not as 'low as possible'. Someone happily working at 10ms reliably will not care if 2ms is theoretically possible in a real world situation.

lowt3ch you have a good product there no doubt but milking the -RT kernel reputation that hard with it's very modest latency gains vs. low-latency really comes across as a bit overwrought and certainly latency is only one of many factors potential users will be interested in. Your quote from Mr. Gleixner could really go both ways as he also concedes that IRQ-threading is a substantial improvement over the stock kernel.

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Re: Do I really need an RT(Real Time) kernel

Post by l0wt3ch »

GMaq wrote:Latency needs to 'low enough' not as 'low as possible'. Someone happily working at 10ms reliably will not care if 2ms is theoretically possible in a real world situation.
My take on it is that "low as possible" means it will be "low enough" for more people. You don't have to use all of its capabilities (it comes with the default JACK settings!), but it's there if you want/need it.
GMaq wrote:lowt3ch you have a good product there no doubt but milking the -RT kernel reputation that hard with it's very modest latency gains vs. low-latency really comes across as a bit overwrought and certainly latency is only one of many factors potential users will be interested in. Your quote from Mr. Gleixner could really go both ways as he also concedes that IRQ-threading is a substantial improvement over the stock kernel.
GMaq, Studio 13.37 doesn't have modest latency gains. It flies! It is built on a micro-Linux that is designed to run in RAM (the whole OS), comes with a super-light desktop environment, and, yes, a realtime kernel. The whole filesystem is less than 400 MB. It's the innovative combination of different elements that make it what it is.

As for Gleixner's quote, I've never denied that IRQ-threading was an improvement. However, I've consistently maintained that anything less than an RT kernel was second-rate. And, if I remember correctly, wasn't Ubuntu Studio dropping RT-kernel support one of the reasons you originally started AVLinux?

brummer

Re: Do I really need an RT(Real Time) kernel

Post by brummer »

My interest in conversation with you is extreme low.
Also, I have give up already to enlighten you in what ever. You have already stated out clearly what you think about non native English speakers and that imply your interest in a international conversation. Well, I know, that those statements from you are already deleted by the forum moderation. But you sign for it it in this post as well. http://www.linuxmusicians.com/viewtopic ... =60#p27424
Anyhow, as soon you start to try telling nonsense, you will receive your feedback from those how interested in the development of Linux Pro Audio .
Maybe you didn't notice that even plain debian already offer a rt-kernel, same as any of the distributors you (well, you didn't) mention here, do that, were you try to imply they do not.
Your entry post to this thread, http://www.linuxmusicians.com/viewtopic ... =30#p27221
was complete nonsense, and I vote for delete it, your next post, http://www.linuxmusicians.com/viewtopic ... =45#p27241
directly start to insult others by Speculation and innuendo.
And the next one http://www.linuxmusicians.com/viewtopic ... =45#p27250
simply try to imply completely wrong conclusions.

(edit: minor censorship by raboof)

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