1754764 - 1.38 - 1.35% Base Content JS / Base Content JS + 2 more (Linux, OSX, Windows) regression on Tue February 8 2022

Status: RESOLVED WONTFIX

(Core :: JavaScript Engine: JIT, defect, P3)

Description

[Andrej (:aglavic)]

Perfherder has detected a awsy performance regression from push 250fa587c2b0099be744469c3ff60fc4e8e79092. 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)
1%	Base Content JS	linux1804-64-shippable-qr		1,785,236.67 -> 1,809,832.00
1%	Base Content JS	windows10-64-2004-shippable-qr		1,786,520.00 -> 1,811,192.00
1%	Base Content JS	macosx1015-64-shippable-qr		1,813,912.00 -> 1,838,488.00
1%	Base Content JS	macosx1015-64-shippable-qr		1,813,912.00 -> 1,838,488.00

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) will be backed out in accordance with our regression policy.

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 1753633

Comment 2

[Jan de Mooij [:jandem]]

This is a typical performance vs memory trade-off unfortunately, I think we'll have to accept this one. We could shrink the cache but that makes it a lot less effective. Another option is lazy initialization and destroying the cache on GC, but that would add more branches and a level of indirection.

Comment 3

[Jan de Mooij [:jandem]]

Closing per comment 2.