[linux-audio-dev] NPTL and real-time sched semantics

Has anyone done any low-latency audio testing with the new native pthread implementation (comes with rh9.0 at least)...? I was just reading through [1] and noticed the following (in section 8): ""Realtime support is mostly missing from the library implementation. The system calls to select scheduling parameters are available but they have no effects. The reason for this is that large parts of the kernel do not follow the rules for realtime scheduling. Waking one of the threads waiting for a futex is not done by looking at the priorities of the waiters."" If I've understood right, SCHED_FIFO semantics do not have any meaning between threads of one process if NPTL is used! Hopefully this is right, as it would cause quite a lot of problems (GUIs and disk i/o threads can freely block audio processing even though using SCHED_FIFO). :( [1] http://people.redhat.com/drepper/nptl-design.pdf -- http://www.eca.cx Audio software for Linux!