LMDE with realtime kernel (64 bit)

adamentos · Post by **adamentos** » Thu Jan 20, 2011 8:18 am

Would really appreciate any help...

Last night I made a new install of LMDE 64 bit on my Lenovo T61

I got my Echo Audiofire8 firewire audio interface connected to and talking via Jack but with serious latency issues with something like 65 milliseconds. Playing with the settings in Jack (Priority...Frames/Period...Periods/Buffer) to bring down latency brought about mayhem and killall'd jackd.

I'm wondering if a realtime kernel would help (everything worked great under the Ubuntu-Studio distro btw which uses rt kernel I think?)

Anyone have any experience with this? I don't see anything in the repositories that looks like a rt kernel. Ubuntu repositories seem to have linux-rt.

Please let me know, otherwise I'll bail and install a 2nd distro on my laptop.

Thanks!!

Adam

willie42 · Post by **willie42** » Thu Jan 20, 2011 8:23 am

usually a Kernel has a number like Linux Headers 2.26.36.X....so if you can find that number its most likely in the repos

adamentos · Post by **adamentos** » Thu Jan 20, 2011 9:18 am

willie42 wrote:usually a Kernel has a number like Linux Headers 2.26.36.X....so if you can find that number its most likely in the repos

I don't see any header that has "rt" in the name so assume there isn't one. Going to try to install Liquorix kernel...

willie42 · Post by **willie42** » Thu Jan 20, 2011 10:51 am

adamentos wrote:
willie42 wrote:usually a Kernel has a number like Linux Headers 2.26.36.X....so if you can find that number its most likely in the repos
I don't see any header that has "rt" in the name so assume there isn't one. Going to try to install Liquorix kernel...

Liquorix Kernel is awesome....

adamentos · Post by **adamentos** » Thu Jan 20, 2011 11:53 am

willie42 wrote:Liquorix Kernel is awesome....

Installed and booted up into the Liquorix kernel but so far I'm not able to get Jack to start up with my firewire audio interface even after adding this to /etc/security/limits.conf

@audio - rtprio 95
@audio - memlock unlimited

since I'm already a member of the "audio" group. I got further along with the default LMDE kernel, any ideas?

bobcollard · Post by **bobcollard** » Thu Jan 27, 2011 3:56 pm

Liquorix is now up to: 2.6.37-0.dmz.6-liquorix-amd64. Have you kept up with the upgrades?

gotjazz · Post by **gotjazz** » Thu Jan 27, 2011 4:42 pm

hrm google finds http://pengutronix.de/software/linux-rt/debian_en.html - can't say more than "google finds it" though

oh - and it's linked on http://wiki.debian.org/DebianMultimedia

jaspaahh · Post by **jaspaahh** » Mon Jul 04, 2011 1:12 pm

A real time kernel is exactly what you need to get your latency down. I've done it in the past, but I forget exactly all the steps involved... There are definitely a lot of tutorials online if you search. You need to recompile the kernel with the -rt patch. Then search for the jack tutorial about how to properly set it up (adding yourself to the @audio group, turning on realtime, setting the 'nice' values etc.)

I've had it working in the past very nicely... ~2 ms. It's a bit of a process to get it going though (as many things are).

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LMDE with realtime kernel (64 bit)

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