[Interest] debug scenegraph batching performance

[Narayanarao Rao]

I have a grid view that I want to optimize. I found that most of the cpu
time is taken in rendering the gridview. I need to make sure scenegraph
batches as many operations as possible. To do this, I set all the env
variables suggested in docs
like QSG_RENDERER_DEBUG=render, QSG_RENDERER_DEBUG=dump etc.

However these give information only in terms of nodes. It is difficult for
me to associate these nodes to actual qml elements. How can I see which qml
elements are getting batched and which are not? I can guess which nodes are
which qml elements but I think there should be a simpler way to get direct
mapping. Here is the debug output with my gridview:

There are 12 elements visible on the gridview, as you can make out from the
below logs:

Renderer::render() QSGRenderer(0xa2c378) "rebuild: none"
Rendering:
 -> Opaque: 12 nodes in 2 batches...
 -> Alpha: 51 nodes in 14 batches...
 - 0xa051f0 [retained] [noclip] [opaque] [  merged]  Nodes:   11  Vertices:
   44  Indices:    66  root: 0x555870
 - 0x9e0d50 [  upload] [noclip] [opaque] [  merged]  Nodes:    1  Vertices:
    4  Indices:     6  root: 0x555870
 - 0x561018 [retained] [noclip] [ alpha] [  merged]  Nodes:    1  Vertices:
    4  Indices:     6  root: 0x0
 - 0x560fe0 [retained] [noclip] [ alpha] [  merged]  Nodes:    1  Vertices:
   12  Indices:    18  root: 0x0
 - 0x9893a8 [retained] [noclip] [ alpha] [  merged]  Nodes:    4  Vertices:
  104  Indices:   156  root: 0x0
 - 0x9d4b40 [retained] [noclip] [ alpha] [  merged]  Nodes:   12  Vertices:
   48  Indices:    72  root: 0x555870
 - 0x5c3128 [retained] [noclip] [ alpha] [  merged]  Nodes:   12  Vertices:
   48  Indices:    72  root: 0x555870
 - 0x989bb8 [retained] [noclip] [ alpha] [  merged]  Nodes:   12  Vertices:
  672  Indices:  1008  root: 0x555870
 - 0x9d63f0 [retained] [noclip] [ alpha] [  merged]  Nodes:    1  Vertices:
    4  Indices:     6  root: 0x0
 - 0xa178f8 [retained] [noclip] [ alpha] [  merged]  Nodes:    1  Vertices:
  148  Indices:   222  root: 0x0
 - 0xa18030 [retained] [noclip] [ alpha] [  merged]  Nodes:    1  Vertices:
   80  Indices:   120  root: 0x0
 - 0x67c170 [retained] [noclip] [ alpha] [  merged]  Nodes:    1  Vertices:
  268  Indices:   402  root: 0x0
 - 0x9dda48 [retained] [noclip] [ alpha] [  merged]  Nodes:    1  Vertices:
  144  Indices:   224  root: 0x0
 - 0x5d3e48 [retained] [noclip] [ alpha] [  merged]  Nodes:    1  Vertices:
    8  Indices:    12  root: 0x0
 - 0x5d3e80 [retained] [noclip] [ alpha] [  merged]  Nodes:    2  Vertices:
   48  Indices:    72  root: 0x0
 - 0x687f48 [retained] [noclip] [ alpha] [  merged]  Nodes:    1  Vertices:
    4  Indices:     6  root: 0x0
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