[PlanetCCRMA] about Fedora updates

Fernando Lopez-Lezcano nando at ccrma.Stanford.EDU
Sat Mar 13 16:44:58 PST 2010

On Sat, 2010-03-13 at 15:12 -0800, Niels Mayer wrote:
> Fernando -- Thank you for your help! I had long fixed the issues with
> improper parameters to Jack, so your message forced me to revisit all
> my old assumptions regarding CCRMA's Jack by re-adding CCRMA to my
> repos and updating to 
>   jack-audio-connection-kit.i686 0:1.9.4-1.fc12.ccrma
>   jack-audio-connection-kit.x86_64 0:1.9.4-1.fc12.ccrma
>   jack-audio-connection-kit-example-clients.x86_64
> 0:1.9.4-1.fc12.ccrma         
> This Jack now starts correctly, but outputs a concerning error
> message; however it works, and worked beautifully until it crashed
> along with rosegarden in the "is it really realtime" part of my test.
> While running, it gave fewer of those inconsequential Xruns that I get
> whenever I have jack playing back music and decide to type an email
> message in gmail.
> The concerning error message is "Cannot use real-time scheduling
> (RR/60)(1: Operation not permitted) // AcquireSelfRealTime error"
> Prior, it says "JACK server starting in realtime mode with priority
> 60."

The Planet CCRMA jack installs some lines in
the /etc/security/limits.conf file that allows all users to access
SCHED_FIFO/RR scheduling - the Fedora jack relies on you being part of
the jackuser group. It looks like you don't have that (caveat: you may
have it, after installing the Planet CCRMA jack package you have to
logout and then login again for that change to take effect). 

Check /etc/security/limits.conf to see if there are lines added at the
end by the Planet CCRMA jack. You should see something like:

## Automatically appended by the Planet CCRMA jack-audio-connection-kit
* - rtprio 99
* - memlock 4194304
* - nice -10

-- Fernando

> Despite the error messages, I see the "RT" indicator flashing in the
> qjackctl display, and even starting mythtv and simultaneously watching
> an HD channel during music playback (something realtime intensive to
> test nonrealtimeness of music playback) only causes **** alsa_pcm:
> xrun of at least 0.666 msecs 13:39:04.515 XRUN callback (4)." once,
> when mythtv starts up while Hydrogen is playing. A second run using
> Rosegarden 10 without all the torture testing resulted in 0 x-runs and
> no crashes. I will continue testing further w/ more audio intensive
> apps later (these were tests were mostly MIDI, or one softsynth and
> sequencer, which is not very challenging).
> Here's the results and logs from the first run that resulted in a
> crash, and a second successful run with Rosegarden (with mythfrontend
> no longer running and displaying off-air HD channel, and also with cpu
> scaling set to "performance" mode). The first run had both mythtv
> playing and was running in CPU "ondemand" mode (0.8G->3.4G CPU freq
> scaling) for maximum realtime torture of Jack. (yes I realize cpu freq
> scaling isn't helpful to realtime performance).
> http://nielsmayer.com/qjackctl-after-upgd-jack-1.9.4-1.fc12.ccrma.log
> Niels
> http://nielsmayer.com

More information about the PlanetCCRMA mailing list