Re: [linux-audio-user] Which kernel for low latency?

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Subject: Re: [linux-audio-user] Which kernel for low latency?
From: Glenn McCord (clari_player_AT_paradise.net.nz)
Date: Mon Jan 19 2004 - 03:51:13 EET

I'm having no luck getting low latency with a 2.6 kernel.
I'm using the mm4 patches and have modified the capabilities.h file.

I have this entered into fstab:
shmfs /dev/shm shm defaults 0 0
none /dev/shm tmpfs defaults 0 0
none /tmp/jack tmpfs defaults 0 0
none /mnt/ramfs tmpfs defaults 0 0

and compiled jack with:
./configure --with-default-tmpdir=/mnt/ramfs --enable-capabilities
--enable-realtime

I want to use ardour so that was just a staight ./configure && make

To run jack I go
jackstart -R -v -d alsa -d hw:0 -p 8192

My problem is that I get
**** alsa_pcm: xrun of at least xx.xxx msecs
all the time. I even get it when no audio programs are going.

On the 2.4.2 I can get jack to run with no -p options at all and it runs
perfectly, hence my anguish.

Cheers for any help. This is pretty much all the stuff I've done so
throw me ANY hints.

James Stone wrote:

>On Sun, Jan 18, 2004 at 11:20:32PM +0000, Glenn McCord wrote:
>
>
>>That link is useful. I've been trying to find out what the mm stood for.
>>And I have sound working now. As it turns out I think I needed to
>>compile in not only:
>><*> EMU10K1 (SB Live! & Audigy, E-mu APS)
>>but...
>><*> (Creative) Ensoniq AudioPCI 1370
>><*> (Creative) Ensoniq AudioPCI 1371/1373
>>aswell.
>>
>>
>
>Interesting. What sound card do you have?
>
>
I have a soundblaster Live but this problem may have arisen from copy
and pasting .config files from 2.6 to 2.6.1-mm4 to 2.6.1, so something
probably came unstuck.

>
>
>>Now I'm off to get jack running but I've had really bad form with that
>>and the 2.6
>>
>>
>
>What problems?
>
>
>
>>Q. With the 2.4 kernel, low-latency was seen to be working by going:
>>cat /proc/sys/kernel/lowlatency
>>
>>but now all I get is:
>>root_AT_upstairs linux # cat /proc/sys/kernel/lowlatency
>>cat: /proc/sys/kernel/lowlatency: No such file or directory
>>
>>How does the 2.6 use low-latency audio? Is it buried deep amongst the
>>features now, and working by default?
>>
>>
>
>As I understand it, low latency features are included in the kernel and
>you don't need to do anything extra.
>
>James
>
>
>
>

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