**This is an old revision of the document!**
OpenCL is an open framework that enables a computer to recruit all manner of other computational devices (such as a GPU and additional CPUs) to distribute a workload. Depending on the hardware you have available, OpenCL can speed up graphics processing by orders of magnitude.
Strengths [Weaknesses]
Parallelism
Your computer potentially has a lot more computing power at its disposal than what you are using. Unlock it with OpenCL.
Weaknesses [Strengths]
Specialised
OpenCL is becoming more common, but for now it is still fairly specialised. Not all applications (or the OS itself, for that matter) utilise OpenCL, and even if they do, OpenCL depends heavily upon the hardware it has available. If your system is not top-of-the-line, you may not see much of a improvement.
Install
Before attempting to get OpenCL up and running, get the specs of your system with cpuinfo and lspci:
$ lspci | grep VGA [...] NVIDIA [Quadro 5000] (rev c2)
Refer to product documentation to determine whether your GPU is OpenCL capable.
$ egrep sse[3456] /proc/cpuinfo flags : fpu vme [...] sse3 [...] sse4_1 [...]
If your CPU returns anything, then it is OpenCL capable.
Installing OpenCL
The OpenCL framework consists of an OpenCL library providing the actual API (the programming bits that applications seeking to use OpenCL will actually use), device drivers (to drive the GPU or other OpenCL capable device), and the OpenCL code compiler and header files (needed to build applications with OpenCL enabled).
Here is what you need to do to get them, and to enable them:
OpenCL Library
OpenCL libraries (the .so files in /usr/lib*) mainly come from Nvidia and AMD (other vendors have implementations, but these are the most-used libs, since these are the two most common high-end graphic cards). OpenCL being an open standard, it does not actually matter which library you use. In fact, the OpenCL library you end up with will most likely be dictated by the GPU you have in your computer; the OpenCL library will come along with the driver that you install.
Therefore, to get the OpenCL library, install a driver for your graphics card. Nvidia drivers are available from http://slackbuilds.org or directly from Nvidia. AMD drivers, such as they are, are available from http://amd.com.
For Intel CPUs and graphic chips, the drivers depend on the specific model; information is on https://software.intel.com/en-us/articles/opencl-drivers.
See Also
MakeHuman
Kdenlive
Lightworks
Natron
Synfig Studio
Mitsuba
Luxrender
Yafaray
povray