Groups > comp.programming.threads > #544

Re: Priority-Inversion

Path	csiph.com!x330-a1.tempe.blueboxinc.net!newsfeed.hal-mli.net!feeder3.hal-mli.net!news.shlink.de!news1.wobline.de!news.bcc.de!newsfeeder.ewetel.de!newsfeed.xs4all.nl!newsfeed6.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!news2.euro.net!feeder.news-service.com!aioe.org!.POSTED!not-for-mail
From	Gerald Breuer <Gerald.Breuer@googlemail.com>
Newsgroups	comp.programming.threads
Subject	Re: Priority-Inversion
Date	Wed, 07 Sep 2011 00:37:29 +0200
Organization	Aioe.org NNTP Server
Lines	25
Message-ID	<j467b9$8oh$1@speranza.aioe.org> (permalink)
References	<j43d2h$709$1@speranza.aioe.org> <4e65be1a$0$7628$9b4e6d93@newsspool1.arcor-online.net> <j45b5r$qud$1@speranza.aioe.org> <4e66950a$0$7623$9b4e6d93@newsspool1.arcor-online.net>
NNTP-Posting-Host	/bBWIQURVgzikp8ykoU1Xw.user.speranza.aioe.org
Mime-Version	1.0
Content-Type	text/plain; charset=ISO-8859-15; format=flowed
Content-Transfer-Encoding	8bit
X-Complaints-To	abuse@aioe.org
User-Agent	Mozilla/5.0 (Windows NT 5.1; rv:6.0.1) Gecko/20110830 Thunderbird/6.0.1
X-Notice	Filtered by postfilter v. 0.8.2
Xref	x330-a1.tempe.blueboxinc.net comp.programming.threads:544

Show key headers only | View raw

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.

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

csiph-web