1617976 - Are we still uploading the dithering texture?

Status: RESOLVED INVALID

(Core :: Graphics: WebRender, defect)

Description

[Markus Stange [:mstange]]

Profile: https://perfht.ml/32p8PsU

My impression was that gradient dithering has been turned off. However, I can see upload_texture_immediate being called from Renderer::new in the profile. There's one call to upload_texture_immediate in the function that I can see and it's uploading the dithering texture. Is this being hit or is the upload in the profile from a different call that's inlined into Renderer::new somehow?

Comment 1

[Glenn Watson [:gw]]

The linked upload call is inside a if options.enable_dithering { branch, so it shouldn't be getting uploaded.

Which suggests either gradient dithering is enabled in that build (unlikely) or it's a different upload. TextureResolver::new (which is called from Renderer::new) does upload a 1x1 dummy texture - perhaps you're seeing that?

Comment 2

[Glenn Watson [:gw]]

To expand on the above, that dummy texture is bound in some cases (I think the input textures in the first pass?) to keep some drivers / GPUs happy that there was no texture bound previously.

Comment 3

[Markus Stange [:mstange]]

I see, yeah it might be the 1x1 dummy texture. Thanks!