Atte Andr? Jensen <atte.jensen@xxxxxxxxx> writes: > 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 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 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... > >> 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. 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. >> 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? I believe so. And their LL kernels probably work very well. But, I can't prove that from personal experience. -- joq
