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Re: Is a CoreAudio bug the cause of the annoying "overload" messages in Logic 8 ?
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Re: Is a CoreAudio bug the cause of the annoying "overload" messages in Logic 8 ?



An overload, in the context of Core Audio, basically means that the HAL's IO thread failed to meet it's real time deadline. The usual cause for this sort of problem is that the IOProc took too long to finish executing. I can't speak to your circumstances without seeing more evidence (e.g. a Shark trace, the IO cycle telemetry, etc), but when I see this happen in apps, it is caused by either them just trying to do too much work in the allocated time or they are doing something silly like blocking on a mutex or something like that.

Note, that the number of CPUs really has no bearing on this phenomenon since there is only one IO thread and it is the amount of time this thread spends running doing the signal processing or whatever that causes overloads.

The usual course for a developer to take when they see overloads that seem to be caused by using their plug-in is to start profiling with Shark, see where the time is being spent, and optimize accordingly. You might want to use AULab to test with to give you a little more control over the environment.

On Mar 4, 2008, at 7:40 AM, Daniel Stenning wrote:

I am naturally trying to use Logic8 as my "reference" sequencer when working
on my AudioUnit plugin project but time and time again when attempting to
play logic songs that incorporate my plugin, I end up getting the dreaded
overload messages.


Take a look here just to see the amount of traffic and heat this problem is
generating:


http://discussions.apple.com/thread.jspa?threadID=1322338&tstart=75

Is it not time this was fixed ?  OSX is meant to be the "musicians"
OS and Logic8 is made by the same company.

Very often this message crops up when using MIDI AU instruments so there
must be something going on here.


We now have 8 core CPUS and a supposedly multicore friendly leopard OS. Yet
Logic8 still seems to be having problems with songs that are hardly taxing
in terms of complexity. What is going on ?.



--

Jeff Moore
Core Audio
Apple


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References: 
 >Is a CoreAudio bug the cause of the annoying "overload" messages in Logic 8 ? (From: Daniel Stenning <email@hidden>)



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