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Re: IOMalloc question

Hi Tony,

On Apr 30, 2007, at 11:58 AM, Tony Wong wrote:


I am using IOMalloc in a media filter driver to allocate buffer for each read, write request.
Data is copied around.

Everything works fine until I ran a heavy read test.  After a few fairly large read requests
(512K size), IOMalloc fails.  That's fine.  I queue the request up and then the driver retries
the IOMalloc in the IOCompletion routine when some previous IOMalloc'ed buffer is freed.
It works a couple times and then it gets stuck.   Then I added some timeout events to
do the IOMalloc periodically but it just fails.  The test hangs.

I also have the impression that IOMalloc() will block until memory is available.  When does it
ever return NULL?  What does that mean?

Is there other way to allocate memory (I am assuming that IOMalloc has a limited pool??)?

IOMalloc is only for small temporary allocations. Otherwise try IOBufferMemoryDescriptor.

--gc
____________________________________________________________________
Garth Cummings  email@hidden
Sr. Software Engineer
Apple Developer Technical Support


WWDC 2007 • June 11-15 • Moscone West • San Francisco, CA

 

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