few words about opencl

Dmytro Konobrytskyi 1

Few words about OpenCL

Dmytro Konobrytskyi


Content

• Introduction• Supported devices• OpenCL “Hello world”• OpenCL vs. CUDA performance• Conclusion / Questions


History

• Open Computing Language (OpenCL) is a framework for writing programs that execute across heterogeneous platforms consisting of central processing unit (CPUs), graphics processing unit (GPUs), and other processors.

• OpenCL 1.0 - 08 December 2008– 5 August 2009, AMD: SDK– 28 September 2009, Nvidia: drivers and SDK

• OpenCL 1.1 - 14 June 2010• OpenCL 1.2 - 15 November 2011


Supported devices

• NVidia GPU– On CUDA architecture

• AMD CPU, GPU, APU• Intel CPU– SSE/AVX support– IGP support starting with Ivy Bridge

• Multi-core ARM CPUs• ZiiLABS (Creative) ZMS processor• Mobile Phone GPUs?


OpenCL Platform Model

http://www.nvidia.com/content/GTC/documents/1409_GTC09.pdf

http://www.nvidia.com/content/GTC/documents/1409_GTC09.pdf


OpenCL memory model


Go to Visual Studio

OpenCL “Hello world”


OpenCL vs. CUDA performance



• How do we have to compare performance?– The same code vs. Optimized algorithms– The latest drivers vs. The most stable drivers– The latest hardware vs. The most popular– Raw math and simple algorithms vs. Real world

complicated algorithm vs. All possible algorithms• We need to remember that NV GPUs actually

use the same set of commands for both CUDA and OpenCL



• There is no the right answer for all these questions and testing requires a lot of time.

• And testing results actually may be not valid with new drivers.

• So we will look on existing testing results available in the web from different people, different algorithms and hardware and we will try to see the trends in these data.


www.sisoftware.net• Typical Arithmetic Results• Environment: Windows Vista x64 SP2; Catalyst 9.11 video / STREAM

1.4.427 / OpenCL 1.0 Beta 4; ForceWare 190.89 video / CUDA 2.3 / OpenCL 1.0 live release.

http://www.sisoftware.net/?d=qa&f=gpgpu_gpu_perf&l=en&a=oca

Sep 2009

http://www.sisoftware.net/



www.sisoftware.net• Typical Memory Bandwidth Results • Environment: Windows Vista x64 SP2; Catalyst 9.11 video / STREAM

1.4.427 / OpenCL 1.0 Beta 4; ForceWare 190.89 video / CUDA 2.3 / OpenCL 1.0 live release.


Sep 2009

http://www.sisoftware.net/



Accelereyes blogMay 2010

http://blog.accelereyes.com/blog/2010/05/10/nvidia-fermi-cuda-and-opencl/

C2050

http://blog.accelereyes.com/blog/2010/05/10/nvidia-fermi-cuda-and-opencl/


Paper: A Performance Comparison of CUDA and OpenCL by Kamran Karimi

• Adiabatic QUantum Algorthms (AQUA), a Monte Carlo simulation

http://arxiv.org/abs/1005.2581

May 2010

Kernel execution and GPU data transfer times in seconds.

http://arxiv.org/abs/1005.2581


Accelereyes webinar

http://blog.accelereyes.com/blog/2012/02/17/opencl_vs_cuda_webinar_recap/

Feb 2012

Accelereyes: Our OpenCL support is new and not nearly as mature as our support of CUDA. But our initial OpenCL support is better than our initial CUDA support was when we first launched our CUDA products. And we expect OpenCL to continue to mature rapidly in the near future.

http://blog.accelereyes.com/blog/2012/02/17/opencl_vs_cuda_webinar_recap/


Kyle Spafford of Oak Ridge National Laboratory:Feb 2012

http://www.cc.gatech.edu/~vetter/keeneland/tutorial-2012-02-20/13-shoc.pdf



Kyle Spafford of Oak Ridge National Laboratory:





• Conclusions:– Performance of simple math operations was the

same initially and the same now;– OpenCL does not have access to few hardware

instructions and algorithms which use them are slower (texture, cache size selection);

– OpenCL uses more accurate special functions by default (but can use native functions);

– OpenCL was slower initially but the modern implementation is as fast as CUDA.


• Conclusion suppose to be here but let’s just discuss it together

few words about opencl

Documents

support of cuda

video cuda

cuda performancethere

cuda performancehow

cuda products

initial cuda support

performance comparison

butour initial opencl