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Thread: Intel Iris Pro problems (Apple MacBook Pro)

  1. #1

    Intel Iris Pro problems (Apple MacBook Pro)

    I've been testing OpenCL v1.2 on an Apple MacBook Pro and have encountered 2 (so far) issues where the Iris Pro behavior seems to be incorrect.
    (1) When sampling an image, the Iris Pro yields a different interpolation to the clamped values. (Clamping specification: CLK_NORMALIZED_COORDS_FALSE | CLK_ADDRESS_CLAMP | CLK_FILTER_LINEAR)
    (2) When using atomic_inc in a kernel the Iris Pro triggers a call to __pthread_kill from clWaitForEvents

    The first issue was awkward (it causes unit tests to fail). The second issue is untenable (it causes unit testing to crash).

    Is there a way to work around this issue other than excluding the Iris Pro?

    P.S. Hardware specifics:
    MacBook Pro (Retina, 15-inch, Mid 2014)
    2.8 GHz Intel Core i7
    NVIDIA GeForce GT 750M 2048 MB
    Intel Iris Pro 1536 MB
    Framework is what Apple provides:
    /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk/System/Library/Frameworks/OpenCL.framework

  2. #2
    Update: Additionally, a declaration of a local variable within kernel code results in a compile failure. (Works as it should for Core i7 and GT 750M.)

  3. #3
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    Hello AngelGabriel, would it be possible to provide more detail about these issues? If you can provide a simple reproducer that would be ideal, otherwise I'll take as much information as you can provide.

    For example:

    1) What built-in function are you using to sample the image? Are you using integer or floating point coordinates? What image channel data type are you sampling?
    2) Do you see this behavior with all kernels using atomic_inc or a specific kernel? If it's a specific kernel, what is it doing?
    3) I presume this is a variable in the __local address space and not any local variable? Are you declaring the __local variable at kernel function scope (see section 6.5.2 of the OpenCL 1.2 spec)?

    You may find a faster response to Intel bug reports by posting to the Intel OpenCL forums, here: https://software.intel.com/en-us/forums/opencl

    We try to monitor other OpenCL forums (like this one) as well, but sometimes things slip through the cracks.

    Thanks!

  4. #4
    @bashbaug thank you for the response... I will put together minimal examples, but it may take me a few days to find the time.

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