[LAU] (Ardour) How to get rid of delay when recording ?

[Ralf Mardorf]

On Sun, 14 Feb 2016 11:05:30 -0500, jonetsu at teksavvy.com wrote:
>The system runs 3.13.0-24-generic (Linux Mint 17 original).  The
>software management tool shows a same lowlatency kernel, so that's OK.

Install this kernel. It might be needed to add 'threadirqs' to the
grub.cfg /boot/vmlinuz line. I don't know when it became the default
for the lowlatency kernel, nowadays it's not required anymore.

Then follow Len's advices:

On Sat, 13 Feb 2016 17:04:45 -0800 (PST), Len Ovens wrote:
>mv /etc/security/limits.d/audio.conf.disabled /etc/security/limits.d/audio.conf

The defaults of Ubuntu might differ to the settings recommended here:

"@realtime   -  rtprio     99
@realtime   -  memlock    unlimited" -
http://www.jackaudio.org/faq/linux_rt_config.html

Consider to edit the values to the above defaults, resp. to

  @audio 	- rtprio 	99
  @audio 	- memlock 	unlimited

Run

  id

if there's no group (audio) shown, you need to add the user to this
group.

>install rtirq.
>
>As you are running a delta1010 (I think), sudo
>edit /etc/default/rtirq... the line that says:
>RTIRQ_NAME_LIST="something something"
>to:
>RTIRQ_NAME_LIST="snd_ice1712"

Reboot and after rebooting run

 /etc/init.d/rtirq status

and post the output here, perhaps you need to unbind one ore the other
thingy.

>Do change your CPU governor from OnDemand to Performance.

To see what governor you are using run

  cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

to set the governor to performance run

  echo performance|sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

>Do find out how to change "swappiness" to 10 rather than 60 so the
>kernel doesn't start preemptive swapping even though it is using less
>than half your RAM

I don't know if this is needed.

Regards,
Ralf