debian stock kernels are not rt. In order to work with lower latencies and boost audio performance you need to patch the generic kernel.
A fix for midi should be in this rt patch http://www.kernel.org/pub/linux/kernel/projects/rt/patch-2.6.26.8-rt16.bz2 (but I am not sure) and higher. Otherwise you can download the patch here http://offog.org/stuff/rt-200901/tasklets-fix-tasklet_hi_action.patch
Actually I am on 2.6.29-rt-vanilla, debian way compiled, on testing/squeeze but I did it on lenny a couple of days after it was released.
When compiling from vanilla sources you must prevent compiler warnings to stop building by checking "Kernel hacking" -> "Continue building despite compiler warnings" and then go with make-kpkg as usual on debian.
regards
r
2009/3/10 alex stone <compose59@xxxxxxxxx>
On Tue, Mar 10, 2009 at 4:06 PM, Cassiel <raffaele.morelli@xxxxxxxxx> wrote:
generic or custom (rt patched) kernel?
r2009/3/10 nescivi <nescivi@xxxxxxxxx>
realtime priorities were handled through limits.conf, and I am running on the
Debian kernel 2.6.26-1-amd64 on a Intel Core2 Duo, T7500 2.20 GHz. (It's a
Lenovo Thinkpad T61).
The previous Debian kernel 2.6.24, did give me better results with JACK, but
had problem with the serial chip driver (the FTDI), at certain baudrates.
So yes, the few xruns were problematic, since my soundtrack was the only sound
that was going on, and I would really like to know how I could make this
whole setup a bit more robust.
The video capturing and the visualisation are certainly less time critical, as
I am only deriving control data from it, and/or using it to monitor. It is
not projected out again.
sincerely,
Marije
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For what it's worth, and i'm certainly not a kernel or linux expert by any stretch of the imagination, I've just built (via the debian build method) an RT kernel from vanilla, and Igno's patches, for 2.6.26-(rt16 build). As i understand it, 2.6.26-rt8, and previous, had a problem with sound and midi. I did read a discussion about this, in which a clever fellow had built a patch to remedy the problems, and it was intimated that this patch would be included in subsequent rt<number> builds.
I don't know if this has happened, but here, on Debian 5 32bit, i'm running jack2, with Alsa 1.0.19, 128-n3, and have no problems. No xruns, or glitches so far. (The kernel is still warm from a few days ago).
I have a question related to this.
Is it possible to build a custom RT kenel using 2.6.29, that will work in Lenny? Is there an incompatability with Glib, or anything else, that will prevent this happening?
Alex.
--
Parchment Studios (It started as a joke...)
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