Re: multithreaded mixer
Re: multithreaded mixer
- Subject: Re: multithreaded mixer
- From: William Stewart <email@hidden>
- Date: Wed, 4 Feb 2004 17:13:49 -0800
On 04/02/2004, at 1:56 PM, Stefan Werner wrote:
Hi,
On 04.02.2004, at 22:22, email@hidden wrote:
Also, let's not forget about the cost of constantly transitioning
between all these threads. This doesn't take a trivial amount of time,
especially since so much state (think about all the FPU and Altivec
registers that need to be saved on a G5) needs to be saved for each
transition. Depending on how you do things, you could easily wipe out
all your gains with managing the overhead.
In short, there's no proper way in which I could make my application
make better use of a dual G5? I put my own non-IOProc related code in
separate threads wherever possible, but the performance bottleneck are
clearly the one dozens of AUConverter and AUVarispeeds that I have
plugged into a Matrix Mixer.
Sure - I think every major host application now uses threading to
utilise more than a single processor for DSP - but this is done very
carefully.
You can think of layers (as Jeff was saying) where different jobs can
be done at different priorities, different times, and so forth. But,
and I think this is the take home point, you have to know what you are
doing, know what locks you are taking, (if any!), which threads are
involved, what their likely contention points are, and so forth. The
fact that several shipping apps do this just fine (and have been for a
number of years) is more than sufficient evidence that it can be done -
its not a question of "can", but "how".
Bill
BTW, any chance of seeing kAudioUnitProperty_RenderQuality being
available for the Varispeed AU in a future release?
Thanks,
Stefan
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