7 Mar
2005
7 Mar
'05
12:50 a.m.
Atte André Jensen <atte.jensen(a)gmail.com> writes:
No. That patch is useful for granting RT privileges to non-root
users, but it has no effect on the inherent latency of the kernel.
I believe so. And their LL kernels probably work very well. But, I
can't prove that from personal experience.
--
joq
To be honest I'm not sure exactly what is the
cause of the problem
(which is why I want to see what an optimized kernel will do), I can
think of:
1) kernel.
possible
2) unnecessary services
unlikely
3) the fact that my soundcard is usb (Edirol UA-1A)
quite possible, but some have reported success with this device, IIRC
4) csound itself (doubt it)
agreed
5) computer. Hope not, it a P4 2.4Ghz laptop
very unlikely
For lowest
latency, 2.6.10 with Ingo Molnar's realtime preemption
patches is currently the best.
That's new for me... You're not talking about this, right?
[atte@aarhus src]$ head linux-2.6.10-rt2.patch I tried applying the above patch, but I didn't see
anything new under
"security" in the kernel config, so I guess I did something wrong...
You should see a new CONFIG_SECURITY_REALTIME option after the patch
is applied. If depends on CONFIG_SECURITY and requires that
CONFIG_SECURITY_CAPABILITES not be built in (=y). I recommend
building it as a module (=m).
Where to get the patches you're talking about, and
what to do?
[1] http://seclists.org/lists/linux-kernel/2005/Feb/1083.html
Not that much, since I'm on a home brewn 2.6.9...
This also means that I
have a working alsa setup. If i wen't with 2.4 I would have to install
alsa seperately, so...
2.6.9 did not have good latency in my tests. 2.6.10 was much better.
Since you're already comfortable building and installing kernels, I
suggest you try 2.6.11 first. Then, if you want to push the envelope
further, try Ingo's patchset[1].
I suspect your USB device will become a latency bottleneck before
these kernels will, but only experimenting on your own system will
tell you for sure.
A recent, stable 2.6.x kernel is also an easy
option. I'm getting as
good or better LL results with vanilla 2.6.10 than with 2.4.19 and the
LL patches. I have not tried 2.6.11 yet, but expect it to be even
better. IMO, latency is no longer a reason to avoid 2.6 kernels.
As mentioned, I'm already on 2.6.9. For the
easiest solution, go with PlanetCCRMA (Fedora/RedHat) or
AGNULA/DeMuDi (Debian). They've got this stuff all integrated and
readily available for binary download.
I'm not interrested in "easy" but in "best". I'm on
debian/unstable, so
maybe agnula would be possible. I just want to make sure that my current
system is not "infected" with all kinds of agnula stuff. Is it possible
just to get the low-latency kernel and use on an unstable system?