[linux-audio-user] 2.6.15.4, realtime-lsm, jackd -R, system performance down!

I just compiled a vanilla kernel 2.6.15.4 in my G3 powerpc. Also I
compiled, installed and loaded the realtime-lsm module and I started
to play with jackd -R and some jack enabled applications.

If I start jackd without realtime, everything runs nicely, of course
with some xruns when I switch windows, manipulate GUIs and such. This
is more or less what I expected.

But then I run jackd realtime using qjackctl. I start amsynth and it
takes a bit longer to load but then runs without a mess. Sound is
clean, no artifacts, no xruns.

Then I try horgand. It takes a lot for it to load, then it sounds
nicely, I get no xruns, but my X Window system becomes unresponsive.

Later I try zynaddsubfx. It takes half an hour to open, and then it
kills qjackctl, leaving the jack server running. Meanwhile top shows
that zynaddsubfx is taking 35% of memory, and qjackctl and jackd 25%
each.

Could this be an issue with the applications, with the kernel, with
the realtime-lsm module, with priority of my X Window session?

I must insist this only happens when jackd is run with the -R option.

Is it true that realtime-lsm is deprecated? How do I enable realtime
preemption on a 2.6.15?

Any ideas welcome.

Cordially, Ismael

-- 
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