Maintaining a Real Time Stable Kernel

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rncbc
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Re: Maintaining a Real Time Stable Kernel

Postby rncbc » Sat Aug 03, 2019 9:34 pm

actually jackdmp aka jackd2 uses multiple threads/cores *iif* the jack graph takes 'parallel' paths; iow: jack clients that are connected consecutively do always use one and only logical thread/core (might migrate across the several available but that's purely os/kernel/cpu scheduler business, not jack's).

qtractor (and also ardour ofc. when set as a jack client): as one single jack client, all pure-DSP/real-time processing will only use one jack-thread/core (the real-time one), no matter what; however, due to their multi-threaded architecture, most non-real-time processing, which includes many several other tasks than just the GUI event-loop for that matter, will take and will be scheduled to run on any other core/thread and none of that related to the "multi-processing" feature of jackdmp/jackd2, whatever.

so whether being called a DAW, or not, is not the point here ;) jackdmp/jackd2 will only take use of more than one core if and only if you have split graph paths.

eg. assuming A, B, C and D are different jack client instances:

1. all clients will run on same core/thread (1 thread/core);

Code: Select all

A --> B --> C --> D

2. all clients *but C* will run on same core/thread (2 thread/cores);

Code: Select all

A -.-> B -+-> D
   '-> C -'


hope to have made it clear now.
cheers

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khz
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Re: Maintaining a Real Time Stable Kernel

Postby khz » Sun Aug 04, 2019 6:37 am

Thanks rncbc.
If this has something to do with it, how does irqbalance (viewtopic.php?p=108966#p108966) relate to audio processing? Is that (still) important?
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tramp
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Re: Maintaining a Real Time Stable Kernel

Postby tramp » Sun Aug 04, 2019 7:10 am

rncbc wrote:so whether being called a DAW, or not, is not the point here ;) jackdmp/jackd2 will only take use of more than one core if and only if you have split graph paths.


Exact, and that was my point here, Ardour does that, you'll find a rt-thread for any track you create in ardour, so, parallel processing is possible when use jackd2.

My stance about qtractor being a DAW or not, was just a joke, for me, it is. :D
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bluebell
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Re: Maintaining a Real Time Stable Kernel

Postby bluebell » Sun Aug 04, 2019 10:52 am

Coming soon:

q.png
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rncbc
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Re: Maintaining a Real Time Stable Kernel

Postby rncbc » Sun Aug 04, 2019 5:26 pm

tramp wrote:Ardour does that, you'll find a rt-thread for any track you create in ardour, so, parallel processing is possible when use jackd2.

my point is that so called Ardour's rt-thread per track are NOT the same as the jackdmp/jackd2 process cycle real-time thread(s), precisely the ones that make up for its multi-processing/core magic ;)

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tramp
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Re: Maintaining a Real Time Stable Kernel

Postby tramp » Sun Aug 04, 2019 9:01 pm

True, but nuitpicking. The result is the same.
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bluebell
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Re: Maintaining a Real Time Stable Kernel

Postby bluebell » Mon Aug 05, 2019 10:12 am

tramp wrote:True, but nuitpicking. The result is the same.


Is it? Can Ardour saturate several CPU cores by just using several tracks with CPU-hungry plugins, for example 32 tracks with a CALF multiband limiter in 4x oversampling mode in each track?
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tramp
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Re: Maintaining a Real Time Stable Kernel

Postby tramp » Mon Aug 05, 2019 1:48 pm

It is. The magic to Split the dsp over several cores is done in jackdmp, but the bare boone requirment therefor is, well, multiple callbacks.
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merlyn
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Re: Maintaining a Real Time Stable Kernel

Postby merlyn » Mon Aug 05, 2019 2:25 pm

I saw this post on the Ardour forum :

Maximum cores ardour can utilize

Paul Davis wrote:The parallelism relies on you having as many (or more) tracks as you do CPU cores. They also need to be independent (i.e. Track 1 does not feed Track 2). Under those circumstances (which are quite typical), you would get full utilization.

However, note that Ardour sessions with 100+ tracks run relatively easily on a 4 core system unless all the tracks are heavily burdened by CPU intensive DSP (like Reverbs and certain kinds of EQ), or digital synthesis.

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khz
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Re: Maintaining a Real Time Stable Kernel

Postby khz » Thu Aug 08, 2019 7:47 am

FZ - Does humor belongs in Music?
GNU/LINUX@AUDIO ~ /Wiki $ Howto.Info && GNU/Linux Debian installing >> Linux Audio Workstation LAW
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Re: Maintaining a Real Time Stable Kernel

Postby bluebell » Thu Aug 08, 2019 10:39 am



Good news. The simpler it is for distributors and users to enable a RT kernel the more non-nerdy users will see the power of Linux for musicians and audio workers. Without iLok and phone-home malware (aka "installers" and "license managers").
Linux – MOTU UltraLite AVB – Qtractor – https://soundcloud.com/suedwestlicht


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