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To: Freebsd hackers list <freebsd-hackers@FreeBSD.org>
From: Yuri <yuri@rawbw.com>
Subject: Why regular user with realtime priority can't run
 pthread_setschedparam(3) with sched_priority=10 ?
Message-ID: <52cf051e-8c8a-d844-2756-9d2079cdd33d@rawbw.com>
Date: Sun, 8 Jan 2017 15:26:59 -0800
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The process (jackd) calls this code:
 >        rtparam.sched_priority = priority; // =10
 >        if ((x = pthread_setschedparam (thread, SCHED_FIFO, &rtparam)) 
!= 0) {

It succeeds when the process is run as 'root'.
It fails when the process is run as a regular user with realtime 
priority (set with rtprio 0): Operation not permitted

Why realtime priority of the process doesn't make high priority threads 
possible?

Yuri