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Date: Sun, 29 Jun 2003 22:32:42 -0400 (EDT)
From: Jeff Roberson <jroberson@chesapeake.net>
To: Petri Helenius <pete@he.iki.fi>
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cc: deischen@freebsd.org
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Subject: Re: rtprio and kse
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On Mon, 30 Jun 2003, Petri Helenius wrote:

> >
> > The rtprio() call affects the KSEG in which the thread runs.
> > So it is the KSEG that has the realtime priority, and all
> > threads that run in that KSEG will be affected.  This doesn't
> > affect other KSEGs, so if you are creating system scope
> > threads (each has their own KSEG and KSE), they will only
> > be affected if you call rtprio() from their threads.
> >
> So if I interpret this correctly, to achieve the "expected" result,
> one should link with -lthr, not -lkse? Expected result being
> priorities apply only to threads which call for it.
>
> Does -lthr have any (known) issues with spinlocks like linuxthreads has, where
> a thread with rtprio going into a spinlock might monopolize the CPU
> and the other thread never gets a quantum to actually release the lock?
>

If you mean spinlock_t, no, there are no issues with that.  There is a
race condition that sometimes leads to deadlocked threads if you use the
pthread mutex.  I expect that to be tracked down and fixed soon.

Cheers,
Jeff