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Thread: Bad performance after transferring from 32 bit to 64 bit

  1. #1
    Junior Member
    Join Date
    Jan 2014

    Bad performance after transferring from 32 bit to 64 bit

    I'm working on both my computers, one of which has a 32-bit Win 7 OS and the other one has a 64-bit Win 7 OS. Both machines have the Intel HD Graphics 4000 GPU inside.
    My kernel works fine with the 32-bit one however, when I transferred it to the 64-bit machine, it is functionally correct but the performance is bad:
    On the 32-bit machine, it takes 27 sec to perform the whole process while on the 64-bit one, it takes 111 sec to do the same thing.
    I didn't change the code and that's why I found it strange. Also, I understand there are some difference between a 32-bit OS and a 64-bit one (like the size of a pointer, etc.) But since the final output is correct, I suppose that it doesn't effect my program here?
    I wonder is it happening to anyone else? Or did I miss something in the transferring?
    Thanks in advance.

    I have just updated my gpu driver to the latest version and the kernel failed to work!
    I got a "clSetKernelArg function for memiRect failed." error and the error code is -51 which indicated a mismatch of arg_size.
    The size of cl_mem is 8 bytes in 64-bit OS and 4 bytes in 32-bit OS. Is this the problem? What should I do to pass the arg in this situation?
    Last edited by leoamuro; 02-10-2014 at 05:21 AM.

  2. #2
    Can you show us your clSetKernelArg call? Does it look like this:

    cl_mem buf = clCreateBuffer....
    clSetKernelArg(kernel, 0, sizeof(cl_mem), &buf)

    Or something different?

  3. #3
    Junior Member
    Join Date
    Jan 2014
    Hi, kunze
    Sorry that I forgot to update this thread. I finally solved this problem by updating the GPU's driver on the 64-bit machine. I guess that's why the performance was so bad. Still, Thank you very much for your reply.

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