In Vulkan, a Blender shader is organized in multiple
objects. A VkPipeline is the highest level concept and represents
somewhat we call a shader. A pipeline is an device/platform optimized
version of the shader that is uploaded and executed in the GPU device.
A key difference with shaders is that its usage is also compiled
in. When using the same shader with a different blending, a new pipeline
needs to be created.
In the current implementation of the Vulkan backend the pipeline is
re-created when any pipeline parameter changes. This triggers many
pipeline compilations. Especially when common shaders are used in
different parts of the drawing code.
A requirement of our render graph implementation is that changes
of the pipeline can be detected based on the VkPipeline handle.
We only want to rebind the pipeline handle when the handle actually
changes. This improves performance (especially on NVIDIA) devices
where pipeline binds are known to be costly.
The solution of this PR is to add a pipeline pool. This holds all
pipelines and can find an already created pipeline based on pipeline
infos. Only compute pipelines support has been added.
# Future enhancements
- Recent drivers replace `VkShaderModule` with pipeline libraries.
It improves sharing pipeline stages and reduce pipeline creation times.
- GPUMaterials should be removed from the pipeline pool when they are
destroyed. Details on this will be more clear when EEVEE support is
added.
Pull Request: https://projects.blender.org/blender/blender/pulls/120899
17c84451b9