[pulseaudio-tickets] [PulseAudio] #91: The jack modules aren't real-time safe.

[PulseAudio]

#91: The jack modules aren't real-time safe.
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 Reporter:  tanuk          |       Owner:  lennart
     Type:  defect         |      Status:  new    
 Priority:  normal         |   Milestone:         
Component:  module-jack-*  |    Severity:  normal 
 Keywords:                 |  
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 The jack modules are unusable in a low-latency setup.

 I have come up with a patch for the sink. For some information that I
 don't see necessary to repeat here, see my message to the list, where I
 posted the first version of the patch:
 http://article.gmane.org/gmane.comp.audio.pulseaudio.general/105

 I was told that writing to a pipe may block, and that it causes an
 undesirable context switch anyway. So I made another version. That didn't
 work. This is the third version, I added an extra thread that takes care
 of writing to the pipe. I would have liked to get away with no new
 threads, since I have no experience of creating threads in a C-like
 environment. So review carefully at least the start_filling_ringbuffer
 function where the thread is created. Not that I have experienced any
 problems, though.

 Another thing I'm not sure: do I have to do any memory locking related
 things? The jack ringbuffer has a locking function, which I have not used.
 Jack automatically locks the clients' memory, present and future, is that
 enough? I think I have read somewhere that all memory should be 'touched'
 before use in the real-time context...

 This time the handling of the jack blocksize changes is tested.

 The file is completely reordered to my liking, so the patch may not be
 very easy to follow. For the reviewer's convenience I have also uploaded
 the resulting file to http://iki.fi/tanuk/tmp/module-jack-sink.c

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Ticket URL: <http://pulseaudio.org/ticket/91>
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