[proaudio] Re: [proaudio] Has anyone experimented with different rlimits values in /etc/security/limits.conf?

[Dominique Michel <dominique.michel@xxxxxxxxxxxx>]

Le Sat, 10 Jun 2006 18:54:51 -0500,
"Colin Shapiro" <cmshapiro@xxxxxxxxx> a écrit :

> Greetings,
> 
> I was just wondering if anyone has played around with different values for
> the rlimits-aware PAM.  I'm asking, because I'm wondering if they can be
> altered for better Jack performance.
> 
> I have an AMD64 X2 with 2GB of RAM, and although Jack performs much better
> now after I've rebuilt and optimized my system, I still consistently get an
> xrun after ~30 minutes of using LinuxSampler with the PMI Bösendorfer 290
> Gig-v3 sample library.

Hum, such problem can be hardware related too. If using APIC, try to
reboot with noapic as boot parameter and check the output of

# cat /proc/interrupts

It must be no shared irq for the sound card even at the PIC level.
http://www.gentoo.org/doc/en/articles/hardware-stability-p2.xml

If all is OK, you can reboot normaly. It can be a good thing too to double-check your kernel configuration.
You can compare too the output of "lspci -v" and "lsmod". You must have only the modules corresponding to your harware. It can append if you have more modules as needed with the kernel at, at boot time, the kernel load concurrent modules for the same hardware (specialy the chipset). It is more an issue with distribution kernel as with a specific kernel as with gentoo.

> 
> I've changed the defaults:
> 
> @audio    -    rtprio 100
> @audio    -    nice -10
> @audio    -    memlock 250000
> 
> ...to this:
> 
> @audio    -    rtprio 100
> @audio    -    nice -20
> @audio    -    memlock 1024000
> 
> ...and I *think* (although I could be imagining things) that it's working a
> little better.  But I'm wondering if anyone else has any insight to offer on
> this.
> 
> Thanks,
> 
> Colin

I have play a little with pam-rlimits and the realtime-lsm. If you have
installed both, it is redundant, and you must and can use only pam-rlimits.
So, it is best to remove or comment out "realtime"
from /etc/modules.autoload.d/kernel-2.6, as well as remove rtirq from
your default runlevel. Run modules-update after the changes and reboot.

With pam-rlimits, I played only with memlock, and it helped to increase the value.

If nothing help, you can try the realtime-lsm. For that to work, all you have to do is to downgrade pam the last non rlimits version:

# emerge -av =pam-0.78-r5

add a line with realtime in /etc/modules.autoload.d/kernel-2.6 and add rtirq in your default runlevel:

# emerge rtirq
# rc-update add rtirq default

add a file /etc/modules.conf/realtime with a line

options realtime gid=18

and run

# modules-update

I get better result with the realtime-lsm as with pam, and it is the recommanded way if you want to do heavy audio work. If you take a look at audio distribution as agnula or planet ccrma, that is the way they work.

Best,
Dominique