Re: App using kext based on AudioReflectorDriver consumes more CPU with internal speakers
Re: App using kext based on AudioReflectorDriver consumes more CPU with internal speakers
- Subject: Re: App using kext based on AudioReflectorDriver consumes more CPU with internal speakers
- From: Stéphane Letz <email@hidden>
- Date: Tue, 15 Nov 2011 21:14:38 +0100
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 15 Nov 2011 11:00:38 +0530
> From: Swetha C <email@hidden>
> Subject: App using kext based on AudioReflectorDriver consumes more
> CPU with internal speakers
> To: email@hidden
> Message-ID: <003801cca357$b52ed7d0$email@hidden>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi,
>
> We have a kext based on Apple's AudioReflectorDriver sample code and an app which is user client for the virtual device.Everything works fine except for the app is consuming more CPU on Mac Book Pro, when the output device is "internal speakers" even when no audio is playing. The scenario is: Mac book pro is idle and internal speakers is the output device, the app consumes around 13% of CPU.Under the same conditions with output device as Headphones, the CPU consumption is around 4%. For both scenarios the app follows the same path.When time profiled with shark, more samples are in AppleHDAEngine::ClipOutputSamples,but for Internal speakers, it is around 76%, with headphones it is around 36%.
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> On Mac Pro (Desktop)the CPU consumption is almost same for both cases and is around 4%.
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> Please help with any pointers.
>
>
>
> Regards,
> Swetha
>
AFAICS audio code path is not the same when using internal speakers : there is some DSP code to protect internal speakers (in kernel mode), and this code consume CPU. You should be able to see that with Shark (here I seed functions like EupDSP:LowCut... etc...)
Best Regards
Stéphane Letz _______________________________________________
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