25 Aug
2025
25 Aug
'25
6:13 a.m.
On August 24, 2025 4:15:37 PM GMT+02:00, Hermann Meyer <brummer-(a)web.de> wrote:
Hi
I running into issues with the jack_is_realtime(client) currently. The issue is, when the
user didn't have permission to run real-time tasks, jackd starts with no real-time
permission but jack_is_realtime(client) reports true as soon the -R is in the jackd
commandline. The same is true for jack_client_real_time_priority(client). This call
reports the real-time priority given in the command line, but not the one in use. So, when
jackd starts without real-time priority, but -R is given on the command-line, it reports
the priority from jackdrc while it runs at SCHED_OTHER without any priority.
Now, when I want to start my own threads I cant relay on the values reported by jackd,
which render the functions useless.
I need to run my own tests in order to check if real-time priority could be set by the
user or not.
regards
hermann
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The documentation for this API call is a little unclear about what it really does:
<https://jackaudio.org/api/group__ClientFunctions.html#ga15719a4abdcc5fa8415167dd6ed6512c>
And one could consider the implementation to be conforming.
I would still consider this a bug though - but rather both in the documentation and the
implementation.
Also wasn't there a difference between jack1 and jack2 in how they handle the failure
to acquire rt scheduling? IIRC jack1 errors out while jack2 just prints a warning.
With jack1 the behaviour then would be precisely what one wants since -R and having this
call returning 1 actually implies having rt scheduling. With jack2 that's not the case
anymore.
Kind regardsv
FPS