2005341 - 7.8 - 7.04% damp jstracer.profiler-recording-performance.DAMP / damp jstracer.profiler-recording-performance.DAMP (Linux, Windows) regression on Mon December 1 2025

Status: RESOLVED WONTFIX

(Core :: JavaScript Engine, defect, P3)

Description

[Treeherder Bug Filer]

Perfherder has detected a devtools performance regression from push f564813850eb211c9b5e05ee5349b5584d877ce4. As author of one of the patches included in that push, we need your help to address this regression.

Please acknowledge, and begin investigating this alert within 3 business days, or the patch(es) may be backed out in accordance with our regression policy. Our guide to handling regression bugs has information about how you can proceed with this investigation.

If you have any questions or need any help with the investigation, please reach out to [e-mail]. Alternatively, you can find help on Slack by joining #perf-help, and on Matrix you can find help by joining #perftest.

Regressions:

Ratio	Test	Platform	Options	Absolute values (old vs new)
8%	damp jstracer.profiler-recording-performance.DAMP	windows11-64-24h2-shippable	e10s fission stylo webrender	139.81 -> 150.72
7%	damp jstracer.profiler-recording-performance.DAMP	linux1804-64-shippable-qr	e10s fission stylo webrender	535.74 -> 573.48

Improvements:

Ratio	Test	Platform	Options	Absolute values (old vs new)
7%	damp custom.jsdebugger.stepInNewSource.DAMP	windows11-64-24h2-shippable	e10s fission stylo webrender	852.20 -> 790.03
6%	damp custom.jsdebugger.stepIn.big-bundle.DAMP	windows11-64-24h2-shippable	e10s fission stylo webrender	1,383.65 -> 1,295.46
6%	damp custom.jsdebugger.stepIn.DAMP	windows11-64-24h2-shippable	e10s fission stylo webrender	1,300.10 -> 1,224.60
5%	damp custom.jsdebugger.stepIn.DAMP	linux1804-64-shippable-qr	e10s fission stylo webrender	2,935.98 -> 2,789.62
4%	damp custom.jsdebugger.stepIn.big-bundle.DAMP	linux1804-64-shippable-qr	e10s fission stylo webrender	3,117.31 -> 2,999.43
...	...	...	...	...
4%	damp custom.jsdebugger.stepInNewSource.big-bundle.DAMP	linux1804-64-shippable-qr	e10s fission stylo webrender	2,284.26 -> 2,203.38

Details of the alert can be found in the alert summary, including links to graphs and comparisons for each of the affected tests.

If you need the profiling jobs you can trigger them yourself from treeherder job view or ask [e-mail] to do that for you.

You can run all of these tests on try with ./mach try perf --alert 47735

The following documentation link provides more information about this command.

Comment 1

[Matthew Gaudet (he/him) [:mgaudet]]

Yeah -- we should investigate this in more detail, but it's not worth a backout for this.

Comment 2

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

Set release status flags based on info from the regressing bug 1997192

Comment 3

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

It has been over 7 days with no activity on this performance regression.

:mgaudet, since you are the author of the regressor, bug 1997192, which triggered this performance alert, could you please provide a progress update?

If this regression is something that fixes a bug, changes the baseline of the regression metrics, or otherwise will not be fixed, please consider closing it as WONTFIX. See this documentation for more information on how to handle regressions.

For additional information/help, please needinfo the performance sheriff who filed this alert (they can be found in comment #0), or reach out in #perftest, or #perfsheriffs on Element.

For more information, please visit BugBot documentation.

Comment 4

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

It has been over 7 days with no activity on this performance regression.

:mgaudet, since you are the author of the regressor, bug 1997192, which triggered this performance alert, could you please provide a progress update?

If this regression is something that fixes a bug, changes the baseline of the regression metrics, or otherwise will not be fixed, please consider closing it as WONTFIX. See this documentation for more information on how to handle regressions.

For additional information/help, please needinfo the performance sheriff who filed this alert (they can be found in comment #0), or reach out in #perftest, or #perfsheriffs on Element.

For more information, please visit BugBot documentation.

Comment 5

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

It has been over 7 days with no activity on this performance regression.

:mgaudet, since you are the author of the regressor, bug 1997192, which triggered this performance alert, could you please provide a progress update?

If this regression is something that fixes a bug, changes the baseline of the regression metrics, or otherwise will not be fixed, please consider closing it as WONTFIX. See this documentation for more information on how to handle regressions.

For additional information/help, please needinfo the performance sheriff who filed this alert (they can be found in comment #0), or reach out in #perftest, or #perfsheriffs on Element.

For more information, please visit BugBot documentation.

Comment 6

[Matthew Gaudet (he/him) [:mgaudet]]

I haven't investigated yet. This will be in my queue for this month

Comment 7

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

It has been over 7 days with no activity on this performance regression.

:mgaudet, since you are the author of the regressor, bug 1997192, which triggered this performance alert, could you please provide a progress update?

If this regression is something that fixes a bug, changes the baseline of the regression metrics, or otherwise will not be fixed, please consider closing it as WONTFIX. See this documentation for more information on how to handle regressions.

For additional information/help, please needinfo the performance sheriff who filed this alert (they can be found in comment #0), or reach out in #perftest, or #perfsheriffs on Element.

For more information, please visit BugBot documentation.

Comment 8

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

It has been over 7 days with no activity on this performance regression.

:mgaudet, since you are the author of the regressor, bug 1997192, which triggered this performance alert, could you please provide a progress update?

If this regression is something that fixes a bug, changes the baseline of the regression metrics, or otherwise will not be fixed, please consider closing it as WONTFIX. See this documentation for more information on how to handle regressions.

For additional information/help, please needinfo the performance sheriff who filed this alert (they can be found in comment #0), or reach out in #perftest, or #perfsheriffs on Element.

For more information, please visit BugBot documentation.

Comment 9

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

It has been over 7 days with no activity on this performance regression.

:mgaudet, since you are the author of the regressor, bug 1997192, which triggered this performance alert, could you please provide a progress update?

If this regression is something that fixes a bug, changes the baseline of the regression metrics, or otherwise will not be fixed, please consider closing it as WONTFIX. See this documentation for more information on how to handle regressions.

For additional information/help, please needinfo the performance sheriff who filed this alert (they can be found in comment #0), or reach out in #perftest, or #perfsheriffs on Element.

For more information, please visit BugBot documentation.

Comment 10

[Matthew Gaudet (he/him) [:mgaudet]]

I'm going to close this as wontfix: We've got other things going on which will probably speed up this test, and digging too deep here is clearly not happening.