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Help understanding some parts of a GPU trace Dx12

Question asked by giordi91 on Feb 17, 2019
Latest reply on Feb 18, 2019 by dipak

Good evening, I started recently using the GPU profiler, and is quite amazing! But there are some things I do not understand.


Please have a look at the below tracer:


Where there is the arrow pointed, I am drawing two meshes exactly in the same position, so event 8 will only generate vertex work, then seems like no pixel shader is generated (early z rejection I suppose?) 
Now the interesting part is that there is a gap between the vertex shader and pixel shader execution. The tutorial I watched on youtube (How-To Use Radeon™ GPU Profiler - YouTube ) Says if there is a gap, it means the shader was stalled for some reason, any chance to know why?

Next question I have is about the barrier (9), after I write to the render texture, I do a bit to the back buffer, that is what event 11 is, I wonder why such a big gap between the end of the pixel shader and the copy? I am currently CPU bound so might just be I am not submitting event fast enough? (It is a simple scene for the time being).
Finally, the green event under barrier 9 is called "CmdDccDecompress" I could not find any hit in the documentation, anyone can explain to me please what it is?

Thank you all!