Re: [LAU] Too many xruns

On 11 October 2012 at 6:55, Paul Davis <paul@email-addr-hidden> 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
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