Multiple Compute Units (Asymmetrical) XRT (XRT Native API's)
============================================================

This is simple example of vector addition to demonstrate how to connect each compute unit to different banks and how to use these compute units in host applications using xrt native api's.

**KEY CONCEPTS:** `Multiple compute units <https://www.xilinx.com/html_docs/xilinx2021_1/vitis_doc/opencl_programming.html#dqz1555367565037>`__


This example demonstrates how to use multiple compute units
of same kernels which are asymmetrical i.e. connected to 
different memory banks.

Kernel can be connected to different banks using vadd.cfg file as below:

::

   [connectivity]
   nk=vadd:4:vadd_1.vadd_2.vadd_3.vadd_4
   sp=vadd_1.in1:DDR[0]
   sp=vadd_1.in2:DDR[0]
   sp=vadd_1.out_r:DDR[0]
   sp=vadd_2.in1:DDR[1]
   sp=vadd_2.in2:DDR[1]
   sp=vadd_2.out_r:DDR[1]
   sp=vadd_3.in1:PLRAM[0]
   sp=vadd_3.in2:PLRAM[0]
   sp=vadd_3.out_r:PLRAM[0]
   sp=vadd_4.in1:PLRAM[1]
   sp=vadd_4.in2:PLRAM[1]
   sp=vadd_4.out_r:PLRAM[1]

Some of the vadd compute units are connected to DDR banks and some are
connected to PLRAMs. ``nk`` option can be used to specify how many
compute unit are needed for ``vadd`` kernel. It also allows to give
names of user choice. ``sp`` option can be used to provide connection of
compute units to target memory (DDR, PLRAM).

``vadd.cfg`` file should be included in v++ command line as below:

::

   --config vadd.cfg

As each compute unit are connected to diferrent DDR/PLRAM, so host
program has to create kernel object specific to compute unit as below:

.. code:: cpp

   xrt::kernel cu0_krnl = xrt::kernel(device, uuid, "vadd:{vadd_1}");

The kernel object which is created above is very specific to ``vadd_1``
compute unit. Using this Kernel Object, host can directly access to this
fix compute unit.

EXCLUDED PLATFORMS
------------------

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

::

   _u25_
   u30
   u50
   u55
   vck
   samsung
   _u2_
   zc
   nodma

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/vadd.cpp
   
Access these files in the github repo by `clicking here <https://github.com/Xilinx/Vitis_Accel_Examples/tree/master/host_xrt/multiple_cus_asymmetrical_xrt>`__.

COMMAND LINE ARGUMENTS
----------------------

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

::

   ./multiple_cus_asymmetrical_xrt -x <vadd XCLBIN>