Re: [LAU] xrun problems. (Was Re: Introduction to Ardour 3.0 MIDI)

Previous message: [thread] [date] [author]
Next message: [thread] [date] [author]
From: jy <jypllx@...>
To: Uwaysi Bin Kareem <uwaysi.bin.kareem@...>
Cc: <linux-audio-user@...>
Date: Wednesday, March 30, 2011 - 7:22 pm

--0015174be87cb9db24049fb8182b
Content-Type: text/plain; charset=ISO-8859-1

My experience is the following :

I had a serious xruns problem using both the internal sound card of my
laptop and my M-Audio MobilePre USB sound card.
After trying a lot of things, the only config that worked for me was to set
my rtprio at priority of the real-time clock minus 11 (so that the jack
watchdog is just under the real-time clock).
These are rather low values : priority is 50 for the rtc and 39 for rtprio
in my limits.conf

but since i set up this configuration, everything runs smoothly at just
under 10 ms using 3 instances of yoshimi, hydrogen, seq24 ardour and
eventually a gx_head with my guitar as input. No xruns at all !!

I used "ps -eo rtprio,cmd" to check the rtc value with my realtime kernel.

hope it can be of any help...

jy

2011/3/30 Uwaysi Bin Kareem

> I found that I could run 0.363 ms latency, quite easily. No dropouts, if

--0015174be87cb9db24049fb8182b
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

My experience is the following :I had a serious xruns problem using=
both the internal sound card of my laptop and my M-Audio MobilePre USB sou=
nd card.After trying a lot of things, the only config that worked for m=
e was to set my rtprio at priority of the real-time clock minus 11 (so that=
the jack watchdog is just under the real-time clock).

These are rather low values : priority is 50 for the rtc and 39 for rtprio =
in my limits.confbut since i set up this configuration, everything =
runs smoothly at just under 10 ms using 3 instances of yoshimi, hydrogen, s=
eq24 ardour and eventually a gx_head with my guitar as input. No xruns at a=
ll !!

I used "ps -eo rtprio,cmd" to check the rtc value with my rea=
ltime kernel.hope it can be of any help...jy2011/3/30 Uwaysi Bin Kareem <uwaysi.bin.kareem@para=
doxuncreated.com
>

I found that I co=
uld run 0.363 ms latency, quite easily. No dropouts, if just running renois=
e.

I did compile a kernel where I turned off all that I could though. What I r=
emember offhand - maximum level of preemption (no need for rt kernel).
Preemptible RCU,
SLAB (doesn't do as much stuff as slub, and probably therefore has lowe=
r latencies)
I didn't find enabling tickless to be a problem.
250hz timer.
Turning off IOMMU's, and similar things. You don't need them on box=
es that has below 4GB RAM. IOMMU adds to latency.
Disabling all debugging, hacking, securtity, and other stuff you don't =
need.

Also you need to make sure that realtime-threads get the highest priority.<=
br>
I also had to modify rtprio to 99 and nice to -20, in /etc/security/limits.=
d/audio.conf on ubuntu natty.

This is my full local config.

http://pastebin.=
com/JCie5RRN

I'm on a core2duo, also using a nvidia gtx280, without problems. 0.363 =
ms latency was with renoise, jackd and konnekt24d.
The kernel is 2.6.36-zen0 http://downloads.zen-kernel.org/snapshots/zen-stable/linux-2.6-zen.v2.6.3=
6-zen0-full-git.tar.gz

I use this because it has some low latency patches, from 38 and 37 on top o=
f 36, which has the old firewire stack.

Peace,
Uwaysi.
_______________________________________________
Linux-audio-user mailing list
=
Linux-audio-user@lists.linuxaudio.org

http://lists.linuxaudio.org/listinfo/linux-audio-user

--0015174be87cb9db24049fb8182b--

Previous message: [thread] [date] [author]
Next message: [thread] [date] [author]

Messages in current thread:
Re: [LAU] xrun problems. (Was Re: Introduction to Ardour 3.0..., Uwaysi Bin Kareem, (Wed Mar 30, 4:11 pm)
Re: [LAU] xrun problems. (Was Re: Introduction to Ardour 3.0..., jy, (Wed Mar 30, 7:22 pm)
Re: [LAU] xrun problems. (Was Re: Introduction to Ardour 3.0..., Fernando Lopez-Lezcano, (Thu Mar 31, 7:45 pm)
Re: [LAU] xrun problems. (Was Re: Introduction to Ardour 3.0..., Fernando Lopez-Lezcano, (Mon Apr 4, 7:03 pm)