[Ardour-Dev] parallelization now in Ardour 3

[Paul Davis]

today, torben merged his work on parallelizing the execution of
processing within Ardour back into the main 3.0 branch. this means
that ardour will:

    * determine how many processors appear to be available
    * create an appropriate number of "worker threads"
    * create a data-flow model of the tracks & busses to determine
when each one can be processed
    * dispatch the threads to work on each "ready" track or bus

therefore, with 2 CPUs and 10 tracks, you can expect to see both CPUs
utilized for processing the tracks, rather than just 1 as happens in
previous versions of Ardour.

some testing has been done while this was all in the 3.0P branch, and
things basically work. however, it will not be a suprise if some
breakage is discovered, hence this warning email. backtraces will be
needed if stuff does go wrong, so be sure to compile with --debug
(this will increase DSP load quite a lot), and have them available for
bug reports etc.

also, while i'm here: please do not use gcc 4.5 to compile ardour in
anything other than debug mode. there are bugs in gcc 4.5 that break
ardour when compiled with almost any level of optimization.

--p