1366175 - Disable validation in ANGLE to enhance WebGL performacne.

Status: NEW

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

Description

[Michael Leu[:Lenzak](UTC+8)]

In gecko's code, we have done validations for WebGL calls, which makes ANGLE's internal validation somewhat redundant, we should try to disable ANGLE's validations.

Comment 1

[Michael Leu[:Lenzak](UTC+8)]

Attachment: Bug 1366175 - Add skip validation attribute when creating ANGLE GL context

Review commit: https://reviewboard.mozilla.org/r/140966/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/140966/

Comment 2

[Michael Leu[:Lenzak](UTC+8)]

We can skip ANGLE's validations in its gl call entrypoints by passing special attribute.

However, skipping these validations has no significant performance improvement.

I am now investigating if ANGLE has other options to disable more validations.

Comment 3

[Michael Leu[:Lenzak](UTC+8)]

I have found that ANGLE has some mandatory validation functions like ValidateDrawElements and ValidateDrawArrays occupied a small but more noticeable time than other validation functions.

https://dxr.mozilla.org/mozilla-central/source/gfx/angle/src/libGLESv2/entry_points_gles_2_0.cpp#762
https://dxr.mozilla.org/mozilla-central/source/gfx/angle/src/libGLESv2/entry_points_gles_2_0.cpp#785

The reason why they cannot be skipped is because they also take charge of calculating the index range of the vertex set for further operations.

I think we will have more noticeable performance gain if we can hack ANGLE to bypass them.

However, it would not be good for further ANGLE update and integration.

Comment 4

[Michael Leu[:Lenzak](UTC+8)]

Attachment: validation_skip_test.txt

Here is some test about the performance difference among different validation skipping schemes.

It appears that the performance difference is not very significant.

I doubt how much can we improve the performance via disabling these validations even with ANGLE modified.

Comment 5

[Michael Leu[:Lenzak](UTC+8)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=364654f3b2da718e3b2b7d67855567fd7576d214

Pushed a try to check whether bypassing these validations will generate regressions or not.

Comment 6

[Michael Leu[:Lenzak](UTC+8)]

It seems that mochitest-gl has no issue after removing these validations,
I think we can disable these validation without harm, maybe land the skip validation attribute patch first since it does not need to modify ANGLE?