1844423 - 3.29% tabpaint (Linux) regression on Fri July 14 2023

Status: RESOLVED WONTFIX

(Core :: Graphics: WebRender, defect)

Description

[Andrej (:aglavic)]

Perfherder has detected a talos performance regression from push e1c387461f1491b8b63445d4505d5617392ed527. As author of one of the patches included in that push, we need your help to address this regression.

Regressions:

Ratio	Test	Platform	Options	Absolute values (old vs new)
3%	tabpaint	linux1804-64-shippable-qr	e10s fission stylo webrender	52.99 -> 54.74

Improvements:

Ratio	Test	Platform	Options	Absolute values (old vs new)
9%	about_preferences_basic	linux1804-64-shippable-qr	e10s fission stylo webrender	165.86 -> 150.87
4%	ts_paint	linux1804-64-shippable-qr	e10s fission stylo webrender	529.04 -> 510.00
3%	startup_about_home_paint_cached	linux1804-64-shippable-qr	e10s fission stylo webrender	979.96 -> 954.42
3%	sessionrestore_no_auto_restore	linux1804-64-shippable-qr	e10s fission stylo webrender	852.42 -> 830.83

Details of the alert can be found in the alert summary, including links to graphs and comparisons for each of the affected tests. Please follow our guide to handling regression bugs and let us know your plans within 3 business days, or the offending patch(es) may be backed out in accordance with our regression policy.

If you need the profiling jobs you can trigger them yourself from treeherder job view or ask a sheriff to do that for you.

For more information on performance sheriffing please see our FAQ.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 1836668

Comment 2

[Darkspirit]

(I'm a tester, not a programmer, this was one of my few patches.)

Software WebRender, HW WR/Xwayland and HW WR/Nvidia already have this behavior (they use the software timer) and require it (bug 1836668 comment 0).
The CI is testing blocklisted force-enabled "hardware" WebRender on llvmpipe (slow software OpenGL) on legacy X11: The new timing seems mostly within 1 frame (1000ms/60fps=16,66ms).
The patch should be kept for complexity reduction and stability (bug 1836668 comment 0), this legacy X11 bug should be wontfixed IIUC.
Wayland (bug 1813588) should be used&tested for best results.

Comment 3

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 1836668