Host Code Organization - 2022.2 English

VSC provides a simple template for application code development and managing software calls to the accelerator hardware. Regardless of the hardware composition this template provides a unified style of creating a C++ software API.

    auto arg1BP  = myACC::create_bufpool( .... ); (1)
    ....
    myACC::send_while([= .... ]() // (2)
    {
        int* arg1 = myAcc::alloc_buf<int>(arg1BP, .... ); // (4)
        ....
        myACC::compute( arg1, .... ); // (5)
        ....
        return ( while_cond ); // (3)
    }
    myACC::receive_all_in_order([= .... ]() // (6)
    {
        ....
    }
    myACC::join(); // (7)

The structure of this template shown in this pseudo-code above has the following parts. Refer to VPP_ACC Class API for details of these elements.

• create_bufpool() - Creates a buffer pool for each pointer argument passed to the accelerator and provides the specification of the argument data (for example: input, output, and remote).
• send_while() - A thread to control the overall scheduling of jobs on the accelerator, providing data for each job by using a lambda function.
• return ( while_cond ); - The body of the lambda function executes in a loop and must return a Boolean value. The return statement in the send_while body allows the user to continue running the loop as long as the value returned is true, and to stop the loop and exit the send_while thread when the value returned is false. A return statement could be (++sent_value<MAX_SEND) if sent_value was set to 0 before declaring and using the lambda function.
• alloc_buf() - Allocation of a memory buffer object from the buffer pool for the current loop iteration.
• compute() - The software call to schedule one job execution of the compute() function on the accelerator hardware.
• receive_all_in_order() - A thread that waits on the results from the scheduled jobs. This is another user-defined lambda function and executes in a loop as long as the send_while() thread runs.
• join() - Waits on the completion of the send and receive threads.

The following sections provide additional details for creating the application code.