System preparation for realtime audio
System preparation for realtime audio
- Subject: System preparation for realtime audio
- From: alejandro <email@hidden>
- Date: Thu, 06 Mar 2008 01:45:50 +0100
Jeff,
We are a post-production DAW manufacturer and we are porting our product
Audiohive (www.openstudionetworks.com) from Linux to OS X.
Our app uses JACK for audio I/O and uses multiple cores for processing.
The processing threads are detached from the JACK callback threads, in a
producer/consumer model, and must have a very good realtime response to
avoid losing audio packets. In Linux there is a way to lock threads to
cores in order to avoid cache and scheduling conflicts. Also interrupts
can be redirected to particular cores (to the ones that are not
processing audio).
There is a lack of these features in OS X, but what I am experiencing is
that all these processing threads, with THREAD_TIME_CONSTRAINT_POLICY
(by far the best I have tried, including the new
THREAD_AFFINITY_POLICY), have a scheduling "stop" every second, so the
CPU meters show a peak. For 512 samples, the peak doubles the percentage
of CPU consumption, but for 256 samples it is tree times more!!!
As you can imagine it is a huge problem for us. Thank you,
Alejandro
--
Alejandro Palencia
Open Studio Networks
+34 667 440 770
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