4 ms·

> Skia is definitely capable of good performance, as it resolves down to OpenGL draw calls, pretty much the same as Alacritty, WebRender, and now xi-mac. This

by jwilm 9y ago

> Skia is definitely capable of good performance, as it resolves down to OpenGL draw calls, pretty much the same as Alacritty, WebRender, and now xi-mac. This claim is a bit surprising to me. I was under the impression Skia is an immediate mode renderer which ends up issuing a lot GL calls that could be avoided with a retained mode renderer.

kllrnohj 9y ago
An immediate-style API does not mean the work is performed immediately. Skia defers and reorders internally to batch commands so minimal GL state changes are required. That said a "lot of GL calls" for a 2D UI is actually a trivially insignificant number of GL calls to the actual GPU/driver for most cases. That's basically never the bottleneck unless you've done something insanely wrong.
- IshKebab 9y ago
  I wouldn't be so sure. A single draw call is surprisingly slow. If you drew each glyph with one draw call that could be hundreds which will definitely cause slowness.
  - kllrnohj 9y ago
    "hundreds" is actually what I meant by insignificant to a modern driver. For example: https://images.anandtech.com/graphs/graph11223/86100.png https://images.anandtech.com/graphs/graph11223/86100.png Granted that's a 1060 but since we're looking at driver CPU overhead that shouldn't matter much. So 2.3 million draw calls per second in DX11 single threaded. It's not until you start getting into the 10k+ draw calls a frame that you are putting your 60fps at risk. It's often worth the work to avoid this anyway, after all faster is better if you're an engine/renderer, but it takes a lot for it to be an actual _problem_
    - IshKebab 9y ago
      Yeah, so 2 million, cut that down by 10 for integrated graphics. Then you need 60 fps, that brings it down to 3000. If you're just doing empty draw calls and nothing else. Throw in WebGL and hundreds is really significant.

4 ms·

> Skia is definitely capable of good performance, as it resolves down to OpenGL draw calls, pretty much the same as Alacritty, WebRender, and now xi-mac. This

by jwilm 9y ago

kllrnohj 9y ago
An immediate-style API does not mean the work is performed immediately. Skia defers and reorders internally to batch commands so minimal GL state changes are required. That said a "lot of GL calls" for a 2D UI is actually a trivially insignificant number of GL calls to the actual GPU/driver for most cases. That's basically never the bottleneck unless you've done something insanely wrong.
- IshKebab 9y ago
  I wouldn't be so sure. A single draw call is surprisingly slow. If you drew each glyph with one draw call that could be hundreds which will definitely cause slowness.
  - kllrnohj 9y ago
    "hundreds" is actually what I meant by insignificant to a modern driver. For example: https://images.anandtech.com/graphs/graph11223/86100.png https://images.anandtech.com/graphs/graph11223/86100.png Granted that's a 1060 but since we're looking at driver CPU overhead that shouldn't matter much. So 2.3 million draw calls per second in DX11 single threaded. It's not until you start getting into the 10k+ draw calls a frame that you are putting your 60fps at risk. It's often worth the work to avoid this anyway, after all faster is better if you're an engine/renderer, but it takes a lot for it to be an actual _problem_
    - IshKebab 9y ago
      Yeah, so 2 million, cut that down by 10 for integrated graphics. Then you need 60 fps, that brings it down to 3000. If you're just doing empty draw calls and nothing else. Throw in WebGL and hundreds is really significant.