Re: [Jack-Devel] jconvolver and OSX

On Mon, Feb 28, 2011 at 7:16 AM, Fons Adriaensen <[hidden]> wrote:

> But if sem_init() does nothing you can't reset an existing one.
> Except by reading the value and then in a loop calling sem_post()
> or sem_wait()... Yuk.

we never use sem_init() for that in actual use. sem_init() is used
exclusively to create/initialize a semaphore, followed by sem_wait and
sem_post. at least by our code.

>> we use these semaphores in ardour3 for multi-threaded graph
>> synchronization. to be fair, however, we have not really tested them
>> much on OS X at this point (though we have verified that they work as
>> expected).
>
> How does A3 distribute processing task over multiple threads ?

data flow graph, involving N threads, one of which functions as the
master (but the precise thread may vary from process cycle to process
cycle). the granularity is an Ardour "route" (basically a bus or a
track). so if you have a 32 track session in which all tracks feed 1
bus and there are no other connections, and you allow ardour to use 8
threads, it will process 8 tracks at a time until they are all done,
then one thread will process the bus, and on the next cycle this
(last) thread will become the master for the next cycle. we wake
threads with sem_post() and they sleep on sem_wait().

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