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Re: Does CoreAudio use the alarm signal in the IO proc thread?
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Re: Does CoreAudio use the alarm signal in the IO proc thread?


  • Subject: Re: Does CoreAudio use the alarm signal in the IO proc thread?
  • From: Jeff Moore <email@hidden>
  • Date: Wed, 24 Jan 2007 10:47:32 -0800

I'm pretty sure that signals are treated specially by the kernel and are not based on Mach message passing.

One other thing that occurred to me is that the signal thing may be a red herring. The real problem may be that some of the constructs that Haskell is using in it's run time might not work correctly on a real time thread, which has special properties, like being of a very high, non-degrading priority. It would be easy enough to test as you can create a test program that spawns a real time thread that can make calls back into the Haskell run time.

On Jan 23, 2007, at 7:23 PM, Herbie Robinson wrote:

At 1:59 PM -0800 1/23/07, Corey O'Connor wrote:
I'm trying to figure out why I cannot use Haskell from a CoreAudio HAL IO proc. One thing Haskell does, which is questionable IMO, is use the alarm signal for it's own thread scheduler. The program is behaving as if the Haskell code is terminating early, but only in the HAL IO proc thread. I think this would be consistent with the Haskell code triggering a signal but instead of the Haskell scheduler recieving the signal another signal handler is triggered. Is it possible that CoreAudio registers it's own signal handler in the IO proc thread? Or are there other caveats to the CoreAudio realtime thread that would account for this behavior?

Signals aren't a native thing for MACH, right?

That would mean they are probably implemented with message passing and something context dependent to catch the messages...


--

Jeff Moore
Core Audio
Apple



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 >Does CoreAudio use the alarm signal in the IO proc thread? (From: "Corey O'Connor" <email@hidden>)
 >Re: Does CoreAudio use the alarm signal in the IO proc thread? (From: Herbie Robinson <email@hidden>)

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