HBM Simple XRT (XRT Native API’s)

This is a simple example of vector addition to describe how to use HLS kernels with HBM (High Bandwidth Memory) for achieving high throughput using xrt native api’s.

KEY CONCEPTS: High Bandwidth Memory, Multiple HBM Banks

KEYWORDS: HBM

This is simple example to demonstrate how to use HBM Platform. Three separate banks are used for each argument of kernels. Individual bank for each buffer will provide more bandwidth for the application.

compute unit interfaces are associated to fixed HBM banks using krnl_vadd.cfg file:

[connectivity]
sp=krnl_vadd_1.in1:HBM[0:3]
sp=krnl_vadd_1.in2:HBM[0:3]
sp=krnl_vadd_1.out_r:HBM[0:3]

It specify that kernel interfaces (in1,in2 and out_r) should be connected such a way that it should have access to HBM banks 0 to 3. System linker will make sure this requirement while building the design.

For Case1, all three buffers (in1,in2, and out_r) will be created inside Single bank and application will run and performance will be reported. For Case2, All three buffers will be created into different banks and application will run and performance will be reported. For Case2, three different banks will give higher DDR bandwidth compare to case1, so performance of Case2 will be better compare to case1. Following is the real log reported while running on U50 platform:

Open the device0
Load the xclbin krnl_vadd.xclbin
Running CASE 1  : Single HBM for all three Buffers
input 1 -> bank 0
input 2 -> bank 0
output  -> bank 0
Allocate Buffer in Global Memory
synchronize input buffer data to device global memory
Execution of the kernel
Get the output data from the device
[CASE 1] THROUGHPUT = 11.1863 GB/s
Running CASE 2: Three Separate Banks for Three Buffers
input 1 -> bank 1
input 2 -> bank 2
output  -> bank 3
Allocate Buffer in Global Memory
synchronize input buffer data to device global memory
Execution of the kernel
Get the output data from the device
[CASE 2] THROUGHPUT = 30.915 GB/s
TEST PASSED

EXCLUDED PLATFORMS

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

_u25_
u30
u200
zc
vck
u250
aws
samsung
_u2_
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/krnl_vadd.cpp

Access these files in the github repo by clicking here.

COMMAND LINE ARGUMENTS

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

./hbm_simple_xrt -x <krnl_vadd XCLBIN>