kern/38750: SCHED_FIFO behaviour does not match POSIX

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>Number:         38750
>Category:       kern
>Synopsis:       SCHED_FIFO behaviour does not match POSIX
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun May 25 22:35:00 +0000 2008
>Originator:     Andrew Doran
>Release:        4.99.63
>Organization:
The NetBSD Project
>Environment:
n/a
>Description:
The behavior of SCHED_FIFO threads doesn't match the specification.
Quote:

--
When a running thread becomes a preempted thread, it becomes the head of the 
thread list for its priority.
--

NetBSD currently does the opposite. It would be good to verify some of
the other requirements are met.


>How-To-Repeat:
Read the spec:

http://www.opengroup.org/onlinepubs/007908799/xsh/realtime.html

I won't cut and paste it here, but see the section with header
SCHED_FIFO.

>Fix:
Match spec.