Comment Re:Yes, but (Score 1) 103
Yes, audio is a bit of a special case, because when the audio hardware needs data, it needs data NOW! That means that the audio thread has to get time from the scheduler and it cant block on some synchronization primative before it completes its job. You can solve that problem using large buffers so that there is plenty of time to prepare the next one before running out. Unfortunately, if you want low latencies, (who wouldn't for a game!) then you cant do that. A good alternative is to instead have "asymmetric multithreading" such that when the audio hardware needs data, it gets unobstructed processor time, on demand, regardless of what is currently occupying the processor.
Asymmetric multithreading (or interrupt level tasks) require a special set of data synchronization primatives. The normal semaphore/mutex will generally cause the high priority thread to block until the low priority one exits a critical region. That is not what you want. You want the audio thread to push through and make the low priority thread move out of the way. Fortunately, atomic operations have this behavior. Making proper use of these tools can be a bit tricky and usually requires that you keep your API simple and straightforward. The current Alsource queue/unqueue is a little bit too complex to do easily with atomic operations. It would be better for this purpose if it was a simple queue (with callbacks, of course!).
Asymmetric multithreading (or interrupt level tasks) require a special set of data synchronization primatives. The normal semaphore/mutex will generally cause the high priority thread to block until the low priority one exits a critical region. That is not what you want. You want the audio thread to push through and make the low priority thread move out of the way. Fortunately, atomic operations have this behavior. Making proper use of these tools can be a bit tricky and usually requires that you keep your API simple and straightforward. The current Alsource queue/unqueue is a little bit too complex to do easily with atomic operations. It would be better for this purpose if it was a simple queue (with callbacks, of course!).
