1328882 - Implement EXT_disjoint_timer_query_webgl2

Status: NEW

(Core :: Graphics: CanvasWebGL, defect, P3)

Description

[Florian Scholz (Open Web Docs)]

https://github.com/KhronosGroup/WebGL/pull/2076 created a new extension called "EXT_disjoint_timer_query_webgl2" which I think you will need if you want to use timer queries in WebGL2.

Spec: https://www.khronos.org/registry/webgl/extensions/EXT_disjoint_timer_query_webgl2/

Chromium implemented this as well: https://bugs.chromium.org/p/chromium/issues/detail?id=654134

It doesn't look like this was implemented in bug 1308057 or was it?

Comment 1

[Jerry Shih[:jerry] (UTC+8) (inactive)]

https://hg.mozilla.org/integration/mozilla-inbound/rev/c4e073f1cb11

I think the EXT_disjoint_timer_query_webgl2 is different from WebGLExtensionID::EXT_disjoint_timer_query.

Comment 2

[julian]

What would be needed to implement this in Firefox? Alternatively, is there a way to profile WebGL2 shader execution in Firefox without this extension?

Comment 3

[Kelsey Gilbert [:jgilbert]]

This extension is required to get GPU timings. We still have code that handles this, we just need to re-audit it for security concerns before we can re-enabled it in a post-spectre world.

Comment 4

[julian]

In the interim, would it be possible to have an about:config setting that enables it? I suspect the primary usecase for GPU timing information is local profiling during development. This would at least match the behavior of the .reduceTimerPrecision. category of flags.

Having a single browser that can get accurate CPU and GPU timings would be invaluable during development.

Comment 5

[Kelsey Gilbert [:jgilbert]]

You should be able to try it if you enable webgl.enable-privileged-extensions, though this is unsafe for the general web.
Note that Firefox does not have a different EXT_disjoint_timer_query_webgl2, and uses EXT_disjoint_timer_query for both webgl1 and webgl2.

Comment 6

[julian]

(In reply to Jeff Gilbert [:jgilbert] from comment #5)

You should be able to try it if you enable webgl.enable-privileged-extensions, though this is unsafe for the general web.
Note that Firefox does not have a different EXT_disjoint_timer_query_webgl2, and uses EXT_disjoint_timer_query for both webgl1 and webgl2.

That's super helpful; thanks! I had tried webgl.enable-privileged-extensions but didn't know to use EXT_disjoint_timer_query.