[LAU] Too many xruns

[Kevin Cosgrove]

On 11 October 2012 at 6:55, Paul Davis <paul at linuxaudiosystems.com> wrote:

> 2.  chrt: failed to set pid 0's policy: Operation not permitted
> >     Checking the ability to prioritize processes with chrt... no - not good
> >     Could not assign a 80 rtprio value. Set up limits.conf.
> >     For more information, see
> >
> > http://wiki.linuxmusicians.com/doku.php?id=system_configuration#limits.conf
> >
> >     I did make the changes outlined at the above link.  I still
> >     get the above report.  I'm going to guess that I need some
> >     real-time support from the kernel to make this work.  Which
> >     brings me to
> 
> this is not true. http://jackaudio.org/realtime_vs_realtime_kernel

OK.  That's a pleasant answer.  :-)

I added this:

::::::::::::::
/etc/security/limits.d/93-audio_limits.conf
::::::::::::::
# Increase priority of audio applications
# maximum realtime priority
@audio - rtprio 90
# maximum locked-in-memory address space (KB)
@audio - memlock 2000000


Fedora's jack-audio-connection-kit-1.9.8-9.fc17.x86_64 package added this:

::::::::::::::
/etc/security/limits.d/95-jack.conf
::::::::::::::
# Default limits for users of jack-audio-connection-kit

@jackuser - rtprio 70
@jackuser - memlock 4194304

@pulse-rt - rtprio 20
@pulse-rt - nice -20

> you *must* get these permissions correct ...

By permissions, are you meaning

  crw-rw---- 1 root audio  10, 228 Oct 10 22:47 /dev/hpet
  crw-rw---- 1 root audio 254,   0 Oct 10 22:47 /dev/rtc0

  [kevinc #28] groups
  kevinc root adm disk wheel cdrom man floppy games audio users jackuser

> > 3.  Kernel with Real-Time Preemption... not found - not good
> 
> not necessarily relevant. required in cases where the kernel and h/w are
> cooperating (badly) to prevent low latency operation, but many people have
> systems where this is not required.

I'm having IRQ crowding issues, and I was headed at trying to
get rtirq going in order to help this.  I believe rtirq *does*
require an RT kernel.
http://wiki.linuxmusicians.com/doku.php?id=system_configuration#rtirq

Thanks....

--
Kevin