[Jack-Devel] JACK 2 is not real time safe on posix?
johannes89 at mailueberfall.de
Sun Apr 19 11:59:15 CEST 2015
it is often being said that JACK 2 is real time safe, for example in the JACK faq. I wondered how JACK 2 suspends a thread, so I checked what happens after the JackClient finished CallProcessCallback():
-> virtual JackSynchro::TimedWait()
However, I found only two classes in the `posix' folder that implement this virtual function:
* JackPosixSemaphore: uses `sem_timedwait()' to block
* JackFifo: uses `read()' to block
However, both `sem_timedwait()' and `read()' are syscalls, so they contain context switch, which means they are non realtime. Actually, the JACK documentation warns to use function like these if you pass a process() callback to jack .
So how can JACK claim it would be realtime? (No objections, I just don't understand it)
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