17.77 - 17.53% ts_paint + 1 more (Linux) regression on Wed April 29 2026

👁 Image	Treeherder Bug Filer Reporter
	Description • 1 month ago
treeherder

Perfherder has detected a talos performance regression from push f6affd94efbcb7de652df67b08e4ad52c437743b. 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.

Regression	Test	Platform	Options	Absolute values [old vs new]
18%	ts_paint (doc)	linux2404-64-shippable	e10s fission stylo webrender-sw	423.08 -> 498.25
18%	ts_paint_webext (doc)	linux2404-64-shippable	e10s fission stylo webrender-sw	422.58 -> 496.67

Support & Actionable Steps

For questions, please contact afinder@mozilla.com. You can also find help on Slack (#perf-help) or Matrix (#perftest).

Action guide details:

• See the guide to handling regression bugs for investigation steps.
• Review the alert summary for affected tests, graphs, and comparisons.
• Check the PerfCompare results.
• Tests on Try: Run all tests using ./mach try perf --alert 49998 (See documentation link for details).
• Profiling jobs: Trigger jobs from Treeherder job view or request them from afinder@mozilla.com.

👁 Image	Tymur Boiko Assignee
	Comment 1 • 1 month ago

At the moment I think that linux startup/paint regressed because Vulkan video capability probing runs an extra synchronous vulkantest subprocess during early gfx/video initialization, same class of work as existing vaapitest probing but additive on the critical path.

👁 Image	Tymur Boiko Assignee
	Comment 2 • 1 month ago

However, media.hardware-video-decoding-vulkan.enabled is false by default, so the vulkantest should not be triggered.
(Must be true for FEATURE_HARDWARE_VIDEO_DECODING_VULKAN to call GetDataVulkan() (and thus run vulkantest)).

👁 Image	Tymur Boiko Assignee
	Comment 3 • 1 month ago

DMABuf:

• AppendDmaBufModifiersFromEGLIfEmpty() was called unconditionally from
  SetModifiersToGfxVars() on X11 startup for P010 and NV12 formats,
  triggering EGL initialisation and two driver round-trips per format
  (~80 ms total) even when hardware video decoding is disabled.

• Move the queries into a new AppendEGLVideoModifiers() method and call it
  from InitPlatformHardwareVideoConfig() only when featureDec.IsEnabled(),
  so machines without hardware video decoding (the default) pay no cost.
  Measured ts_paint regression: +75 ms on Linux (Bug 2036839).

👁 Image	Phabricator Automation
	Updated • 1 month ago

👁 Image	Tymur Boiko Assignee
	Comment 4 • 1 month ago

Most likely AppendDmaBufModifiersFromEGLIfEmpty() is called unconditionally from SetModifiersToGfxVars() on X11 startup for P010 and NV12, triggering EGL initialisation and two driver round-trips even when hardware video decoding is disabled. Provided a patch, please try if the above patch helps

👁 Image	Pulsebot
	Comment 5 • 1 month ago

Pushed by stransky@redhat.com: https://github.com/mozilla-firefox/firefox/commit/04a81dc2cdeb https://hg.mozilla.org/integration/autoland/rev/27fb0bd2aeeb DMABuf - Defer EGL modifier queries to after hardware video decoding is enabled. r=stransky

👁 Image	Pulsebot
	Comment 6 • 1 month ago

Pushed by abutkovits@mozilla.com: https://github.com/mozilla-firefox/firefox/commit/5e7ae585d5a9 https://hg.mozilla.org/integration/autoland/rev/c275d15ee06b Revert "Bug 2036839 - DMABuf - Defer EGL modifier queries to after hardware video decoding is enabled. r=stransky" for causing bustages in DMABufFormats.cpp.

👁 Image	Atila Butkovits
	Comment 7 • 1 month ago

Backed out for causing bustages in DMABufFormats.cpp.

Backout link: https://hg.mozilla.org/integration/autoland/rev/c275d15ee06b

Push with failures: https://treeherder.mozilla.org/jobs?repo=autoland&resultStatus=testfailed%2Cbusted%2Cexception%2Cretry%2Cusercancel&revision=27fb0bd2aeeb496dc7637e6d381ac7f831747f46&selectedTaskRun=TnSXfOjVT0-PpLONMfFhbQ.0

Failure log: https://treeherder.mozilla.org/logviewer?job_id=564432245&repo=autoland&task=TnSXfOjVT0-PpLONMfFhbQ.0&lineNumber=66371

👁 Image	Tymur Boiko Assignee
	Comment 8 • 1 month ago

Let me take a look at this fix, I'll submit an updated version in the next few hours.

👁 Image	Tymur Boiko Assignee
	Comment 9 • 1 month ago

DMABuf:

• AppendDmaBufModifiersFromEGLIfEmpty() was called unconditionally from
  SetModifiersToGfxVars() on X11 startup for P010 and NV12 formats,
  triggering EGL initialisation and two driver round-trips per format
  (~80 ms total) even when hardware video decoding is disabled.

• Move the queries into a new AppendEGLVideoModifiers() method and call it
  from InitPlatformHardwareVideoConfig() only when featureDec.IsEnabled(),
  so machines without hardware video decoding (the default) pay no cost.
  Measured ts_paint regression: +75 ms on Linux (Bug 2036839).

👁 Image	Martin Stránský [:stransky] (ni? me)
	Comment 10 • 1 month ago

Great. Tymur, is it the final version I shall review and land or are you going to do more changes here?
Thanks.

👁 Image	Tymur Boiko Assignee
	Comment 11 • 1 month ago

Please see an updated commit

👁 Image	Tymur Boiko Assignee
	Comment 12 • 1 month ago

Sorry, my last submitted version created a duplicate revision.
The latest version to land is D298517.

👁 Image	Pulsebot
	Comment 13 • 1 month ago

Pushed by stransky@redhat.com: https://github.com/mozilla-firefox/firefox/commit/92ab17043ca3 https://hg.mozilla.org/integration/autoland/rev/cf9e03a3dbd6 DMABuf - Defer EGL modifier queries to after hardware video decoding is enabled. r=stransky

👁 Image	Cosmin Sabou [:CosminS]
	Comment 14 • 1 month ago
bugherder

https://hg.mozilla.org/mozilla-central/rev/cf9e03a3dbd6

👁 Image	Ryan VanderMeulen [:RyanVM]
	Updated • 1 month ago

👁 Image	BMO Github Automation
	Comment 15 • 1 month ago

Authored by https://github.com/t-boiko
https://github.com/mozilla/enterprise-firefox/commit/04a81dc2cdeb229586c2826295d3bf4a6b2858d7
[enterprise-main] Bug 2036839 - DMABuf - Defer EGL modifier queries to after hardware video decoding is enabled. r=stransky

Authored by Atila Butkovits
https://github.com/mozilla/enterprise-firefox/commit/5e7ae585d5a964f34c38dac2393c8ae488d6e1e6
[enterprise-main] Revert "Bug 2036839 - DMABuf - Defer EGL modifier queries to after hardware video decoding is enabled. r=stransky" for causing bustages in DMABufFormats.cpp.

Authored by https://github.com/t-boiko
https://github.com/mozilla/enterprise-firefox/commit/92ab17043ca3a8c384856180acc8b722cceb99dc
[enterprise-main] Bug 2036839 - DMABuf - Defer EGL modifier queries to after hardware video decoding is enabled. r=stransky

👁 Image	Florin Bilt
	Comment 16 • 1 month ago

(In reply to Cosmin Sabou [:CosminS] from comment #14)

https://hg.mozilla.org/mozilla-central/rev/cf9e03a3dbd6

Perfherder has detected a talos performance change from push cf9e03a3dbd6bbdac4b7ca1126533d65384e2ce7.

No action is required from the author; this comment is provided for informational purposes only.

Improvement	Test	Platform	Options	Absolute values [old vs new]
13%	ts_paint_webext (doc)	linux2404-64-shippable	e10s fission stylo webrender-sw	502.58 -> 436.75
12%	ts_paint (doc)	linux2404-64-shippable	e10s fission stylo webrender-sw	480.96 -> 425.17
8%	sessionrestore_no_auto_restore (doc)	linux2404-64-shippable	e10s fission stylo webrender-sw	771.21 -> 709.25
6%	startup_about_home_paint (doc)	linux2404-64-shippable	e10s fission stylo webrender-sw	947.25 -> 886.83

Need Help or Information?

If you have any questions, please reach out to fbilt@mozilla.com. Alternatively, you can find help on Slack by joining #perf-help, and on Matrix you can find help by joining #perftest.

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

👁 Image	Phabricator Automation
	Updated • 1 month ago

👁 Image	Mihai Boldan, Desktop QA [:mboldan]
	Updated • 26 days ago