Re: [LAU] Fwd: [linux-audio-user] Real-time kernel

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To: A list for linux audio users <linux-audio-user@...>
Date: Tuesday, June 26, 2007 - 2:33 pm

Hi Chuck,
A few comments embedded below.
- MArk

On 6/26/07, Chuckk Hubbard wrote:

> 64studio:/mnt/win/Linux# uname -a

OK, running 64-bit. I do also, although I'm Gentoo.

I'm not certain from this kernel name that this is a real-time kernel.
Most of the time they include some form or '-rt' in the name. Not a
requirement that the name say -rt but if you're not running a real
time kernel then all bets are off for real time performance.

>

> 00:14.2 Audio device: ATI Technologies Inc SB450 HDA Audio (rev 01)

> 02:00.0 Ethernet controller: Marvell Technology Group Ltd. 88E8038 PCI-E

OK, so you are running the Intel-HDA which lots of other folks have
had problems with. My son's machine has one and has trouble with
real-time performance although I haven't tried to fix it yet.

>

OK, looking at the list above you have a *lot* of modules loaded.
Again, not necessarily a problem but when I see things like

> thermal 15376 0

this makes me think about power management which has caused me and
others problems with RT performance over the years. Do you need them?
At least for debugging it might be wise to not use anything you don't
absolutely need until you get to the root of the problem.

>

> 16: 429 IO-APIC-fasteoi eth0, HDA Intel

You are sharing the sound card's hardware interrupt line with a NIC.
If this is a desktop machine you might want to change the NIC's slot
and share it with something else for simplicity.

>

> Creating link /home/chuckk/.kde/socket-64studio.

And finally it seems that Jack is not running with real-time turned
on. If it was I would expect to see

/usr/bin/jackd -R .......

Check how you are starting Jack in QJC. There is a button you must
push to turn on real time performance.

Also I'm thinking that someone else recently said they had to run the
Intel-HDA with variables like:

-r48000 -n3

or possibly

-r44100 n3

You should Google a bit for specifics on that. Some on-board sound
cards don't work well at all sample rates.

Hope this helps,
Mark

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Messages in current thread:
[LAU] Fwd: [linux-audio-user] Real-time kernel, Chuckk Hubbard, (Sun Jun 24, 9:01 pm)
Re: [LAU] Fwd: [linux-audio-user] Real-time kernel, Loki Davison, (Mon Jun 25, 1:12 am)
Re: [LAU] Fwd: [linux-audio-user] Real-time kernel, Chuckk Hubbard, (Mon Jun 25, 1:59 am)
Re: [LAU] Fwd: [linux-audio-user] Real-time kernel, Loki Davison, (Mon Jun 25, 2:05 am)
Re: [LAU] Fwd: [linux-audio-user] Real-time kernel, Chuckk Hubbard, (Tue Jun 26, 7:09 am)
[LAU] Re: Real-time kernel, Free Ekanayaka, (Sun Jun 24, 11:32 pm)
Re: [LAU] Re: Real-time kernel, Chuckk Hubbard, (Tue Jun 26, 7:16 am)
Re: [LAU] Fwd: [linux-audio-user] Real-time kernel, Mark Knecht, (Sun Jun 24, 9:37 pm)
Re: [LAU] Fwd: [linux-audio-user] Real-time kernel, Chuckk Hubbard, (Tue Jun 26, 9:26 am)
Re: [LAU] Fwd: [linux-audio-user] Real-time kernel, Paul Coccoli, (Tue Jun 26, 2:35 pm)
Re: [LAU] Fwd: [linux-audio-user] Real-time kernel, Ken Restivo, (Wed Jun 27, 9:16 am)
Re: [LAU] Fwd: [linux-audio-user] Real-time kernel, Loki Davison, (Wed Jun 27, 12:15 pm)
Re: [LAU] Fwd: [linux-audio-user] Real-time kernel, Arnold Krille, (Wed Jun 27, 1:23 pm)
Re: [LAU] Fwd: [linux-audio-user] Real-time kernel, Mark Knecht, (Tue Jun 26, 2:33 pm)
Re: [LAU] Fwd: [linux-audio-user] Real-time kernel, David Adler, (Tue Jun 26, 1:33 pm)