guenter geiger <[EMAIL PROTECTED]> writes: > For 2.6 there is another possibility, the realtime kernel module by > Jack O'Quin (who is on the debian-multimedia list too and has provided > us already with important insights into the working of JACK). > Using this module the applications do not have to be changed. > They can just use their "normal" priority settings mechanism. > > Its downloadable at: > http://www.joq.us/realtime/
One of the permission options provided by this module is `gid=29', which grants realtime privileges to any process belonging to group `audio'. This fits the Debian structure nicely. I believe this approach could form *part* of a systematic solution to the overall realtime privileges problem. The missing piece is a corresponding solution for 2.4 kernels, which will continue being used with audio for a long time. It still runs better (when patched) for low latencies, though with 2.6.3 latency is improving. AFAIK, 2.4 is still the default kernel for sarge, right? The obvious solution would be to apply the rather large SELinux patch from NSA. This back-ports the entire LSM structure to 2.4. I doubt the Debian kernel maintainers would approve of that idea, and IMHO it is overkill for the small changes needed to grant realtime access. To my mind, a more practical solution for 2.4 would be something like the `schedmlockpatch' kernel patch Kjetil Matheussen posted on LAD a while back. For this approach to be adopted by a major distribution like Debian multimedia, I would recommend doing some additional work to make the permission methods for both kernel versions look and behave similarly. I would control them through the same interface in /proc/sys/kernel (or some place like that). I have done some thinking about this. There was a good discussion on LAD a few months back. If there is interest I will make a specific proposal, and maybe come up with a modified 2.4 patch for people to experiement with. -- joq
