Host Global Bandwidth¶
Host to global memory bandwidth test
This example tests the data transfer bandwidth between host and global memory for 3 cases : host to global memory transfer, global memory to host transfer and bidirectional transfer. For PCIe platform case, Host and device are connected via PCIe interconnect and latency of this interconnect can be seen as the acceleration tax for the application. Hence, these transfers should be efficiently managed.
For bandwidth test, clenqueueMigrateMemObjects() API is used to
transfer the data from host to global memory and vice versa.
err = commands.enqueueMigrateMemObjects(mems1, 0/* 0 means from host*/);
err = commands.enqueueMigrateMemObjects(mems2, CL_MIGRATE_MEM_OBJECT_HOST);
Following is the real log reported while running the design on U200 platform:
Platform Name: Xilinx
Found Device=xilinx_u200_xdma_201830_1
INFO: Reading ./build_dir.hw.xilinx_u200_xdma_201830_1/krnl_host_global.xclbin
Loading: './build_dir.hw.xilinx_u200_xdma_201830_1/krnl_host_global.xclbin'
OpenCL migration BW host to device: 4.70066 MB/s for buffer size 0.0625 KB with 1024 buffers
OpenCL migration BW device to host: 4.91932 MB/s for buffer size 0.0625 KB with 1024 buffers
OpenCL migration BW host to device: 19.9712 MB/s for buffer size 0.25 KB with 1024 buffers
OpenCL migration BW device to host: 20.0787 MB/s for buffer size 0.25 KB with 1024 buffers
OpenCL migration BW host to device: 37.3776 MB/s for buffer size 0.5 KB with 1024 buffers
OpenCL migration BW device to host: 39.6291 MB/s for buffer size 0.5 KB with 1024 buffers
OpenCL migration BW host to device: 68.5495 MB/s for buffer size 1 KB with 1024 buffers
OpenCL migration BW device to host: 76.4584 MB/s for buffer size 1 KB with 1024 buffers
OpenCL migration BW host to device: 294.746 MB/s for buffer size 4 KB with 1024 buffers
OpenCL migration BW device to host: 313.529 MB/s for buffer size 4 KB with 1024 buffers
OpenCL migration BW host to device: 1169.25 MB/s for buffer size 16 KB with 512 buffers
OpenCL migration BW device to host: 1114.67 MB/s for buffer size 16 KB with 512 buffers
OpenCL migration BW host to device: 6488.24 MB/s for buffer size 1024 KB with 8 buffers
OpenCL migration BW device to host: 9732.36 MB/s for buffer size 1024 KB with 8 buffers
OpenCL migration BW host to device: 6619.78 MB/s for buffer size 1024 KB with 64 buffers
OpenCL migration BW device to host: 10072.4 MB/s for buffer size 1024 KB with 64 buffers
OpenCL migration BW host to device: 6793.51 MB/s for buffer size 1024 KB with 256 buffers
OpenCL migration BW device to host: 11194.7 MB/s for buffer size 1024 KB with 256 buffers
OpenCL migration BW host to device: 6808.51 MB/s for buffer size 2048 KB with 8 buffers
OpenCL migration BW device to host: 10376.1 MB/s for buffer size 2048 KB with 8 buffers
OpenCL migration BW host to device: 7713.63 MB/s for buffer size 2048 KB with 64 buffers
OpenCL migration BW device to host: 11583.7 MB/s for buffer size 2048 KB with 64 buffers
OpenCL migration BW host to device: 7621.88 MB/s for buffer size 2048 KB with 256 buffers
OpenCL migration BW device to host: 11527.4 MB/s for buffer size 2048 KB with 256 buffers
OpenCL migration BW host to device: 7233.73 MB/s for buffer size 16384 KB with 64 buffers
OpenCL migration BW device to host: 11455.5 MB/s for buffer size 16384 KB with 64 buffers
OpenCL migration BW host to device: 7432.3 MB/s for buffer size 262144 KB with 4 buffers
OpenCL migration BW device to host: 12112 MB/s for buffer size 262144 KB with 4 buffers
OpenCL migration BW host to device: 7452.04 MB/s for buffer size 524288 KB with 2 buffers
OpenCL migration BW device to host: 12128.5 MB/s for buffer size 524288 KB with 2 buffers
The bandwidth numbers for bidirectional case:
OpenCL migration BW overall:8.46482 MB/s for buffer size 0.0625 KB with 1024 buffers
OpenCL migration BW overall:33.3023 MB/s for buffer size 0.25 KB with 1024 buffers
OpenCL migration BW overall:66.912 MB/s for buffer size 0.5 KB with 1024 buffers
OpenCL migration BW overall:129.132 MB/s for buffer size 1 KB with 1024 buffers
OpenCL migration BW overall:524.969 MB/s for buffer size 4 KB with 1024 buffers
OpenCL migration BW overall:1990.79 MB/s for buffer size 16 KB with 512 buffers
OpenCL migration BW overall:13039.9 MB/s for buffer size 1024 KB with 8 buffers
OpenCL migration BW overall:14733 MB/s for buffer size 1024 KB with 64 buffers
OpenCL migration BW overall:15262.2 MB/s for buffer size 1024 KB with 256 buffers
OpenCL migration BW overall:14065.9 MB/s for buffer size 2048 KB with 8 buffers
OpenCL migration BW overall:14935 MB/s for buffer size 2048 KB with 64 buffers
OpenCL migration BW overall:15399.2 MB/s for buffer size 2048 KB with 256 buffers
OpenCL migration BW overall:14626.7 MB/s for buffer size 16384 KB with 64 buffers
OpenCL migration BW overall:14904.3 MB/s for buffer size 262144 KB with 4 buffers
OpenCL migration BW overall:14906.7 MB/s for buffer size 524288 KB with 2 buffers
TEST PASSED
EXCLUDED PLATFORMS:
All Versal Platforms, i.e vck190 etc
All NoDMA Platforms, i.e u50 nodma etc
All Embedded Zynq Platforms, i.e zc702, zcu102 etc
Alveo U50
Alveo U55
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/kernel.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
./host_global_bandwidth <krnl_host_global XCLBIN>