You're blocking ads, which pay for BlenderNation. Read about other ways to support us.

Collaboration and Open Source at AMD: Blender Cycles


The AMD blog features an in-depth post on the work they did on Blender Cycles. In particular, they broke up the Cycles kernel into 10 smaller kernels, and they optimized the pre-processing step from CPU into a much, much faster GPU implementation. Interesting stuff to read!

This article is part of an occasional series about what developers can do when they collaborate. AMD is a real believer in open source projects. Our developers actively contribute to and maintain a variety of open source projects, from highly optimized math libraries to… well, let’s talk about Blender Cycles.

AMD undertook to improve the support for GPU compute inside Blender Cycles. Prior to this effort, the GPU kernel used for rendering was monolithic and huge. As a result of the kernel’s size, the generated code had to spill/unspill registers. These spill/unspill operations cause slower performance, and reduced occupancy. (Occupancy represents the actual number of waves running on the GPU simultaneously. More is better.)

In addition to producing inefficient code, the compiler would sometimes not successfully complete the build, or would generate incorrect code that could lead to black screens or a kernel hang. These are certifiable “bad things.”

About the Author

Avatar image for Bart Veldhuizen
Bart Veldhuizen

I have a LONG history with Blender - I wrote some of the earliest Blender tutorials, worked for Not a Number and helped run the crowdfunding campaign that open sourced Blender (the first one on the internet!). I founded BlenderNation in 2006 and have been editing it every single day since then ;-) I also run the Blender Artists forum and I'm Head of Community at Sketchfab.


    • I have a laptop with a intel HD iGPU that support OpenCL and is fast and consume low power, would be nice that Blender and Intel work for that Cycles work in this GPUs,

  1. Yes, after years and years of ATI users claims... So mostly thanks to those old ATI users for their persistence considering that they will can no longer use these benefits in their "now" old cards. By the way, Linux is Open Source. I hope ATI can read on time the claims of Linux ATI users about the very poor performance of all ATI drivres in Linux, especially in Steam games.

    • Three years claiming amd people to give a little support.
      When closed forum in blender amd I realized I had to buy nvidia.

  2. After a lot of headaches with AMD to run on my linux machine... I found a simple solution, I went back to the store and bought a NVIDIA...
    It works perfectly on my machine, I had no problem to install the drivers on Linux and works perfectly in Blender...
    Sorry to be rude, really sorry, but fu#$ you AMD.

    • I had an hd4850 that was not supported in windows 8 (wasn't that old when windows 8 was out) and of course no opencl support anywhere.
      Gave them a second chance with an hd6870 in a hope they will work their opencl issues but when that happened the card got too old to support their fix
      so I'm done with amd they had their chance with me and they screwed up too many times...
      Now I have a gtx680 and I'm more than happy with it!

Leave A Reply

To add a profile picture to your message, register your email address with To protect your email address, create an account on BlenderNation and log in when posting a message.