Hi Ralf, On Jul 24, 2011, at 4:12 AM, Ralf Mardorf wrote: It's not "emulation". A big part of the RT patch (e.g. threaded IRQ handlers) was been merged into 2.6.39. The goal of the Preempt-RT patch is to eventually end up completely in the vanilla (aka mainline) kernel. http://lwn.net/Articles/440064/ is a nice read on the current state of it. I've been running 2.6.39 ever since it came out and used it for production. I can't tell a difference between it and the rt-patched 2.6.33 for general audio/video production. Neither will produce x-runs - unless I do sth stupid or overload the system. Threaded IRQ handling of the audio-interface and [high priority] FIFO scheduling are the important parts for low-latency audio and they're mainline in 2.6.39 (FIFO scheduling was for a long time already). There's a lot of small (but complex) things the RT patch does that are not in mainline yet (e.g pre-emptible memory-management, sleeping spinlocks) and can improve the guaranteed response-time of dedicated [audio] processes. However the gain [of code available in RT vs what is already mainline] is rather small when compared to latency requirements of audio (us vs. ms) and thus can be neglected on most systems. It'll probably give you an edge though. Long story short: If you just want to make music: stick with 2.6.39 or 3.0 - If you have the time and ability to debug: give 3.0-rt3 a go. Even though the impact of the RT-preemt patch on pro-audio is becoming less dramatic. It's a great project and important project. 2c, robin