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MN_'s avatar
MN_
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7 years ago

Can I read and write buffers simultaneously with OpenCL.

Hello, I am using the FPGA board de5net from Terasic with a Stratix V FPGA. It is connected the to host via PCIe. To obtain a hight throughput I want to read an write buffers simultaneously but unf...
Nooraini_Y_Intel's avatar
Nooraini_Y_Intel
Icon for Frequent Contributor rankFrequent Contributor
7 years ago

​Hi,

Currently I am reviewing the forum for any open questions and found this thread. I apologize that no one seems to answer this question that you posted. Since it has been a while you posted this question, I'm wondering if you have found the answer? If not, please let me know, I will try to assign/find someone to assist you. Please do expect some delay in response as most of our agents are out of office due to the year-end holidays. Thank you.

Regards,

Nooraini

  • MN_'s avatar
    MN_
    Icon for New Contributor rankNew Contributor
    7 years ago

    Hi,

    thank you very much for your answer.

    Unfortunately I have not found an answer for my problem. I already use two different queues and perform the read/write operations in a non-blocking fashion as HRZ recommends it. But when I analyze the execution times, I can see that all commands where executed consecutively.

    I also asked the Terasic suppoort but they didn't answer yet.

    So I really would appreciate it if you could help me.

    Regards

    MN.

    • Nooraini_Y_Intel's avatar
      Nooraini_Y_Intel
      Icon for Frequent Contributor rankFrequent Contributor
      7 years ago

      Hi MN.,

      Noted. I will need time to assign/find someone to assist you. Please do expect some delay in response from the assigned agent.

      Thank you.

      Regards,

      Nooraini

    • HRZ's avatar
      HRZ
      Icon for Frequent Contributor rankFrequent Contributor
      7 years ago

      @MN.​ Can you post a psuedo code, or better yet, all of your host code so that we can take a look at it and give you a more concrete solution?

    • MN_'s avatar
      MN_
      Icon for New Contributor rankNew Contributor
      6 years ago

      Hi,

      here is my host program. It calls a kernel which does nothing.

      The program creates two buffers for writing and two for reading. Then it performs the following tasks:

      1. Write the first buffer
      2. a) Write the second buffer, b) execute the kernel on the first buffer
      3. a) Read the result of the first kernel execution, b) execute the kernel on the second buffer, c) write new data into the first buffer.
      4. a) Read the result of the second kernel execution, b) execute the kernel on the first buffer
      5. a) Read the result of the third kernel execution

      The tasks in every line should be performed simultanously. But from the following times you can see, that the tasks were performed consecutively:

      Start[ns] End[ns] Duration[ns] Transfer rate [GB/s]

      1. Write: 0 391938194 391938194 1.27571

      1. Kernel: 392105739 2001510415 1609404676 0.310674

      1. Read: 2474213273 2768932996 294719723 1.69653

      2. Write: 2001533350 2289509772 287976422 1.73625

      2. Kernel: 2768969091 3323809512 554840421 0.90116

      2. Read: 4051312696 4233617466 182304770 2.74266

      3. Write: 2289595551 2474174001 184578450 2.70888

      3. Kernel: 3323830854 4051289376 727458522 0.687324

      3. Read: 4233661025 4415740370 182079345 2.74606

      Do you know, how to overlap the tasks?

      Thank you very much.