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merlion
Journeyman III

Will the flag of clCreateBuffer influence the results?

Hi,

I'm optimizing the myocyte in Rodinia Benchmark on APU A10-7850K. I want to try different buffer flags.

The original buffer is like this:

        d_initvalu = clCreateBuffer(context,                                    // context

                                                                CL_MEM_READ_WRITE,                        // flags

                                                                d_initvalu_mem,                         // size of buffer

                                                                NULL,                                           // host pointer (optional)

                                                                &error ); 

I change the flag to CL_MEM_READ_WRITE|CL_MEM_ALLOC_HOST_PTR but the output results is different from original results.

Would the flag influence the results?

Thanks!

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5 Replies
tzachi_cohen
Staff
Staff

Re: Will the flag of clCreateBuffer influence the results?

This flag by itself should not influence the results. Can you share more about what the application is doing?

Additionally, please run memtest86 on your DDR3 memory to verify it has no faults.

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merlion
Journeyman III

Re: Will the flag of clCreateBuffer influence the results?

Myocyte application models cardiac myocyte (heart muscle cell) .

http://www.cs.virginia.edu/~skadron/wiki/rodinia/index.php/Myocyte

I am trying to find out the reasons.


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jtrudeau
Staff
Staff

Re: Will the flag of clCreateBuffer influence the results?

As Tzachi noted, the flag should have no impact on the results. One thing that can is memory. As opposed to discrete graphics, on APUs the user may choose to install low grade memory modules that lead to GPU memory corruption. So please run Memtest86 on your system and confirm that your DDR3 memory modules are fine.

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merlion
Journeyman III

Re: Will the flag of clCreateBuffer influence the results?

Hello,

sorry for the late testing. I run the memtest86 2 times and no errer found. I paste the screen shot as follows:

Then what should I do?

IMG_3070.JPG

IMG_3072.JPG

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jason
Adept III

Re: Will the flag of clCreateBuffer influence the results?

On the off chance you use the rect copy functions somewhere:

clEnqueueWriteBufferRect does not work when region width is not equal to src pitch: broken again in ...

Yes, under specific circumstances that flag has been known to change things up.  Now what can happen with an APU specifically with regards to that I'm not sure.

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