2 Jul
2013
2 Jul
'13
6:53 p.m.
Dear colleagues ;)
I have some troubles - read xruns - with this setup:
archlinux - linux-rt(various versions)-jack-presonus1818VSL
My aim is to get as low latency as possibile.
I have tried various kernel versions (rt) and various JACK setups
(48000/(256,128,64),3)
but none of them was without xruns when running:
pd - plugins - ardour
now I am compiling time by time kernel from series 3.2 - because I've read
they are good for this purpose - and I am trying...
Does anybody have some experience with similar setup and with no xruns ?
thanks
fero
2 Jul
2 Jul
7:49 p.m.
On Tue, Jul 2, 2013 at 5:53 PM, Fero Kiraly <fero.kiraly(a)gmail.com> wrote:
I have some troubles - read xruns - with this setup:
There's a lot more to removing Xruns from a system than just the kernel and
JACK settings (although they are very important :)
Known things that need to be done:
-Interrupt requests of your hardware must be prioritized (rtirq script
helps here)
-Interrupt thread handlers (on RT kernel) must be prioritized
-Thread priorities must be checked for JACK itself
Some other things to look into are:
-CPU scaling (causes Xruns here, although others say it works fine)
-WiFi (must be disabled here: "iwconfig wlan0 txpower off", not just
disconnected)
-Graphics chip drivers (I'm using a standard xf86-video driver for my ATI
HD2400XT)
That's a good start anyway: If I find some time, I'll write a quick post on
tuning an Arch system for maximum low-lat RT performance.
My aim is to get as low latency as possible.
Please specify... How low is low :D I've achieved 0.3ms at 96kHz, running a
CPU stress test on each core without Xruns, so I'm pretty happy with
that... since the hardware (Echo Indigo DJ PCMCIA) can't handle any lower!
but none of them was without xruns when running:
pd - plugins - ardour
PD is a bit of a xrun hog on my machine here: not bashing PD, I probably
don't have it set up with ideally. But perhaps try running eg Ardour on its
own for testing purposes? Or another simple app which isn't as dependent on
the "patch" that's loaded..?
HTH, -Harry
8:27 p.m.
On 07/02/2013 07:49 PM, Harry van Haaren wrote:
On Tue, Jul 2, 2013 at 5:53 PM, Fero Kiraly
<fero.kiraly(a)gmail.com> wrote:
* linux 3.2.35-2 PREEMPT RT
(debian's RT kernel recompiled with VSL1818 clock selector fix added)
* jackd 1.9.10 (git)
* Rui's rtirq script
* jackd with -p64 -n2 (actually jackdbus)
* presonus 1818VSL
-> very reliable no x-runs
I have some troubles - read xruns - with this
setup:
There's a lot more to removing Xruns from a system than just the kernel
and
JACK settings (although they are very important :) Known things that need to be done:
-Interrupt requests of your hardware must be prioritized (rtirq script
helps here)
-Interrupt thread handlers (on RT kernel) must be prioritized
-Thread priorities must be checked for JACK itself
+1, +1, +1
Some other things to look into are:
-CPU scaling (causes Xruns here, although others say it works fine)
no problem here w/freq scaling. I have disabled C1E halt states and EIST
in the Bios, though.
-WiFi (must be disabled here: "iwconfig wlan0
txpower off", not just
disconnected)
Nor does wifi + networkmanager cause issues here.
but in either case the 1818VSL here is on a dedicated hardware IRQ - not
shared with any other devices.
-Graphics chip drivers (I'm using a standard
xf86-video driver for my ATI
HD2400XT)
Intel graphics here.
2c,
robin
3 Jul
3 Jul
10:09 a.m.
On 07/02/2013 08:27 PM, Robin Gareus wrote:
On 07/02/2013 07:49 PM, Harry van Haaren wrote:
Hi Robin,
So with and USB2.0 audio interface like the 181VSL using -n2 yields a
stable setup too, no need anymore to use -n3?
On Tue, Jul 2, 2013 at 5:53 PM, Fero Kiraly
<fero.kiraly(a)gmail.com> wrote:
* linux 3.2.35-2 PREEMPT RT
(debian's RT kernel recompiled with VSL1818 clock selector fix added)
* jackd 1.9.10 (git)
* Rui's rtirq script
* jackd with -p64 -n2 (actually jackdbus) I have some troubles - read xruns - with this
setup:
There's a lot more to removing Xruns from a system than just the kernel
and
JACK settings (although they are very important :) * presonus 1818VSL
-> very reliable no x-runs
I have yet to encounter a BIOS that has these options.
Regards,
Jeremy
Known things that need to be done:
-Interrupt requests of your hardware must be prioritized (rtirq script
helps here)
-Interrupt thread handlers (on RT kernel) must be prioritized
-Thread priorities must be checked for JACK itself
+1, +1, +1
Some other things to look into are:
-CPU scaling (causes Xruns here, although others say it works fine)
no problem here w/freq scaling. I have disabled C1E halt states and EIST
in the Bios, though.
10:31 a.m.
On 07/03/2013 10:09 AM, Jeremy Jongepier wrote:
On 07/02/2013 08:27 PM, Robin Gareus wrote:
I don't know if that's USB-2.0 or something else.. - The same goes for
the statement that "USB devices should perform better if the sample
rate is divisible by the period size". I cannot find any evidence that
supports that statement.
As with all complex systems, I trust measurements more than theory:
http://robin.linuxaudio.org/tmp/vsl1818latency.png
(x-axis are permutations of jackd's -p, -n, --sync parameters,
no x-runs with either configuration but it's just jackd + jack_delay,
no load).
[Surprisingly]? the latency increments are not quantized to
milliseconds (as the USB protocol implementation would suggest it should).
On 07/02/2013 07:49 PM, Harry van Haaren wrote:
Hi Robin,
So with and USB2.0 audio interface like the 181VSL using -n2 yields
a stable setup too, no need anymore to use -n3?
On Tue, Jul 2, 2013 at 5:53 PM, Fero Kiraly
<fero.kiraly(a)gmail.com> wrote:
* linux 3.2.35-2 PREEMPT RT (debian's RT kernel recompiled with
VSL1818 clock selector fix added) * jackd 1.9.10 (git) * Rui's
rtirq script * jackd with -p64 -n2 (actually jackdbus) I have some troubles - read xruns - with this
setup:
There's a lot more to removing Xruns from a system than just
the kernel and JACK settings (although they are very important
:) 
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days inactive
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4 comments
5 participants
participants (5)
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Fero Kiraly -
Harry van Haaren -
Jeremy Jongepier -
Robin Gareus -
Robin Gareus