Stream Multiple Compute Units

This is a simple vadd Kernel design in which multiple compute units of kernel are directly communicating with host using stream interfaces.

KEY CONCEPTS: Read/Write Stream, Create/Release Stream

KEYWORDS: cl_stream, CL_STREAM_EOT, nk

This is a simple vadd Kernel design in which multiple compute units of kernel are directly communicating with host using stream interfaces.

For this examples, four compute units of a kernel is created. krnl_stream_vadd.ini file specifies number of compute units along with name of each compute unit as below:

[connectivity]
nk=krnl_stream_vadd:4:vadd_1.vadd_2.vadd_3.vadd_4

This file is included to v++ command line using following statement:

--config krnl_stream_vadd.ini

Host is written configurable for number of compute units using top level const variable NCU:

auto constexpr NCU = 4;

User just needs to change NCU to some other value to make the host code ready for other numbers. But user still needs to manually update the krnl_stream_vadd.ini file for other configuration.

For multiple compute units case, host codes needs to create kernel object using specific compute unit name as below:

std::string cu_id;
std::string krnl_name = "krnl_stream_vadd";
std::vector<cl::Kernel> krnls(NCU);
for (int i = 0; i < NCU; i++)
{
    cu_id = std::to_string(i + 1);
    auto krnl_name_full = krnl_name + ":{" + "vadd_" + cu_id + "}"; //kernel name with compute unit name
    krnls[i] = cl::Kernel(program, krnl_name_full.c_str());
}

Here compute unit should match to name provided in krnl_stream_vadd.ini file.

Once we have unique kernel object for each compute unit, host code can easily creates stream object for respective kernel object and transfer data accordingly. For More details about streaming kernel usage, please refer streaming_simple example.

EXCLUDED PLATFORMS

Platforms containing following strings in their names are not supported for this example :

zc
xdma
xilinx_u250_qep
aws
samsung

DESIGN FILES

Application code is located in the src directory. Accelerator binary files will be compiled to the xclbin directory. The xclbin directory is required by the Makefile and its contents will be filled during compilation. A listing of all the files in this example is shown below

src/host.cpp
src/krnl_stream_vadd.cpp

COMMAND LINE ARGUMENTS

Once the environment has been configured, the application can be executed by

./vadd_stream <krnl_stream_vadd XCLBIN>