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Re: Priority-Inversion

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Am 06.09.2011 23:47, schrieb Marcel Müller:

>> I aked for a practical problem, not for a explanation what PI is;
>> I'm aware of the theoretical problem.

> This is not only theory. It happens really always.

There might be real examplex but what you told before is pure theory.

> If you have a thread that feeds the S/G DMA registers of a sound device
> with physical addresses of audio buffers. If you pass the buffers from
> the application thread to the device driver thread using an ordinary
> queue protected by a mutex then the sound get drop outs under system
> load long before the driver runs out of buffers because of the priority
> inversion. The behavior is nearly the same as if the driver thread runs
> at the lower priority of the application thread.

In this case every part of the chain that feeds some output must be
a realtime thread. So priority inversion isn't the real problem here.

> So either you need a lock free queue or you have to raise the priority
> of the application thread before it acquires the mutex.

Even with a lockfee queue and a feeding thread that isn't also realtime
you could get dropouts.

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Thread

Priority-Inversion Gerald Breuer <Gerald.Breuer@googlemail.com> - 2011-09-05 22:56 +0200
  Re: Priority-Inversion Gerald Breuer <Gerald.Breuer@googlemail.com> - 2011-09-06 03:15 +0200
  Re: Priority-Inversion Marcel Müller <news.5.maazl@spamgourmet.com> - 2011-09-06 08:30 +0200
    Re: Priority-Inversion Gerald Breuer <Gerald.Breuer@googlemail.com> - 2011-09-06 16:36 +0200
      Re: Priority-Inversion Marcel Müller <news.5.maazl@spamgourmet.com> - 2011-09-06 23:47 +0200
        Re: Priority-Inversion Gerald Breuer <Gerald.Breuer@googlemail.com> - 2011-09-07 00:37 +0200
          Re: Priority-Inversion Marcel Müller <news.5.maazl@spamgourmet.com> - 2011-09-07 12:06 +0200
      Re: Priority-Inversion Lewis NH2 <lew.nh2@googlemail.com> - 2011-09-09 09:56 -0700
  Re: Priority-Inversion Hallvard B Furuseth <h.b.furuseth@usit.uio.no> - 2011-09-06 12:34 +0200

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