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[[Image(http://xpra.org/icons/opencl.png)]] [/wiki/CSC CSC]
= OpenCL =

== Warning: this module has been removed in version 2.x ==

This [/wiki/CSC CSC] module takes advantage [http://www.khronos.org/opencl/ OpenCL] backends to parallelize the conversion process and speed things up.
Backends are available for many types of {{{GPU}}}s and {{{CPU}}}s.

The [/wiki/CSC/Performance performance] of the OpenCL backends vary widely, generally speaking {{{GPU}}}s have the edge over {{{CPU}}}s despite the added cost of having to transfer the data to and from the {{{GPU}}}. More importantly, whilst the {{{GPU}}} is busy doing CSC, the {{{CPU}}} is free for other tasks, which reduces overall system load and latency.
}}}

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== {{{csc_opencl}}} Installation ==

As of v0.11, the {{{OpenCL}}} module is installed by default, but to actually use this module you must ensure that {{{OpenCL}}} and providers are installed on your system, which is beyond the scope of this project.

At runtime, the server should detect the availability of {{{OpenCL}}} and print the platforms and devices it chose:
{{{
PyOpenCL loaded, header version: 1.2, GL support: False
 using platform: NVIDIA CUDA (NVIDIA Corporation)
 using device: GPU: GeForce GTX 760 (OpenCL 1.1 CUDA / OpenCL C 1.1 )
}}}
}}}

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== Links ==
* this module relies on [http://documen.tician.de/pyopencl/ PyOpenCL]
* original feature request ticket with more information: #422
* [/browser/xpra/trunk/src/xpra/codecs/csc_opencl csc_opencl module source]
}}}

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== Module Options ==
* select which device type is used as backend using:
{{{
XPRA_OPENCL_DEVICE_TYPE=devicetype xpra start ...
}}}
Where `devicetype` is either {{{GPU}}} or {{{CPU}}}. [[BR]]
* choose the {{{OpenCL}}} implementation to use when more than one are installed:
{{{
XPRA_OPENCL_PLATFORM="Intel" xpra ...
}}}
* select a specific {{{OpenCL}}} device when more than one is available:
{{{
XPRA_OPENCL_DEVICE_NAME="GeForce GTX 760" xpra ...
}}}

To get more information use:
{{{
xpra -d opencl start ...
}}}
(versions older than v0.12 required the use of the {{{XPRA_OPENCL_DEBUG=1}}} environment variable)
}}}