Subject: Re: [linux-audio-dev] priority inversion & inheritance
From: Kai Vehmanen (kai.vehmanen_AT_wakkanet.fi)
Date: Fri Jul 12 2002 - 02:44:59 EEST
On Fri, 12 Jul 2002, Martijn Sipkema wrote:
> This is correct. Even if the thread C is running in another application
> and doesn\'t share any resources with A and B it will still be able to
> preempt A (whilst holding the mutex) and thus block C indefinately. This
> is called priority inversion. In any realistic environment there will
> always be a thread C.
Will there? I think the situation is just the opposite. Only very few apps
run with either SCHED_FIFO or SCHED_RR. And for a good reason, because by
using these scheduling modes you basicly turns your Linux system into a
fancy variation of msdos where badly behaving user-processes can deadlock
your machine. Currently only audio apps (and usually not by default),
cd-burners and some media playsr use SCHED_FIFO.
But ok, ok, running the app's s_f threads at same priority does makes
sense.
-- http://www.eca.cx Audio software for Linux!
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