I tried searching on google, but I need to apply “effects” as in mathematical equations (especially sine waves) for around 8192 values. All of this should ideally be around a few milliseconds, but should not take longer than 10ms.
Similarly, I need to run Input on 8192 values too. This most likely will happen with memcpy, from one array to another, but this might take longer as it can have multiple inputs (network/serial/usb).
In this case, I have to guarantee, that both steps before outputting do not take longer than around 25 ms.
Is there a way to definitely limit these functions to timeframes, so they will be killed/returned if taken to long?
I cannot spawn new threads for each input/effect step, as it takes some time to build these threads. Both methods will be called in a loop, directly after another, so they will run approx. 30-45 times a second.
Whats the way to limit these? I can surely guarantee the read-time where I copy a buffer, but running maths operations seems like something that could potentially take too long.
Realtime-Operating Systems also can somehow guarantee those times, so whats the way here?
(BTW, this all is going to run on a minimal debian linux system, with the GUI decoupled from the actual mehhanism.)
One of my ideas would be to pre-calculate those values in some other thread, lets say the next 100 ops for a given value and then just replay them, so I have some buffer.
Other ideas?
There is no reason your IO and your math etc needs to run in the same thread. I am not talking about launching a new thread every IO, I’m talking about 2 threads with appropriate synchronization. Also do not forget about the autoparallel, autovectorize, openmp, and fastmath options you have too. Especially for arrays you probably want to make sure your compiler is using vectorization. Also choosing data sizes will affect the chunk size of the vector instructions too. That is, float will probably process faster then double. fastmath will probably accelerate things a lot too.
Keep in mind too that you don’t actually have to use threading to launch an IO operation and then go off an do computing, then come back and later wait for IO completion or for that matter probably abort it too. There are IO calls that can run in the background. Forgot what they are called (async io?), but they exist. Threading may be easier though depending on your exact needs, or maybe both so you just have more IO control.