[linux-audio-user] alsa rme96 jack - 186 msec latency?

Georg Rudolph georg.rudolph at schwaben.de
Wed Sep 14 14:51:01 EDT 2005

Lee Revell wrote:
>On Sun, 2005-09-11 at 05:11 +0200, Michael Rudolf wrote:
>>Another point is shared memory; I have that enabled in the kernel, I
>>have a 
>>tmpfs mounted on /dev/shm, and Jack is compiled with support ("JACK 
>>compiled with System V SHM support."), but I have read that Jack
>>uses /tmp 
>>for pipes per default, and I can in fact see some 
>>in /tmp/jack-[uid]/default/. Now /tmp is a normal ext3 file system
>>not a tmpfs. Could that alone be the problem? 
>Yes, that is almost certainly the problem.
>The /tmp entry in /etc/fstab should look like this:
>tmpfs           /tmp            tmpfs   defaults                0       0
>Any decent distro should do this by default.
These discussions makes me think and before I guess too much, I'ld
better ask:

When enabling in ardour 0.9beta29 Display -> Show waveforms while
recording I see a steady increase in memory occupation during recording
(10 channels) 'till my ram is exhausted: ardour/jack are crashing. I run
a patched 2.6.13-rc7 kernel. But:

Now, I think, could it be, that ardour needs for the wave-forms display
proportional to the recording memory in /dev/shm (which is limited to
half the physical ram). At long recordings, this will crash. Could it
be, that jack should not be compiled to run with tmpfs, but instead
should be compiled to run with a tmp file system on ext2. ext2 I have
already for the wave data.

Will a DAW need miminum two partitions with different file systems, one
journalling for everything and an ext2 for the critical audio data? Is
this the way to go in future?

Or is this linear memory increase during recording/displaying wave forms
something for the ardour list?

BTW: ardour is great,

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