2036839 - 17.77 - 17.53% ts_paint + 1 more (Linux) regression on Wed April 29 2026

Status: RESOLVED FIXED

(Core :: Audio/Video: Playback, defect)

Description

[Treeherder Bug Filer]

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 [e-mail]. 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 [e-mail].

Comment 1

[Tymur Boiko]

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.

Comment 2

[Tymur Boiko]

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)).

Comment 3

[Tymur Boiko]

Attachment: Bug 2036839 - DMABuf - Defer EGL modifier queries to after hardware video decoding is enabled. r?stransky

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).

Comment 4

[Tymur Boiko]

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

Comment 5

[Pulsebot]

Pushed by [e-mail]:
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

Comment 6

[Pulsebot]

Pushed by [e-mail]:
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.

Comment 7

[Atila Butkovits]

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

Comment 8

[Tymur Boiko]

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

Comment 9

[Tymur Boiko]

Attachment: Bug 2036839 - DMABuf - Defer EGL modifier queries to after hardware video decoding is enabled. r?stransky

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).

Comment 10

[Martin Stránský [:stransky] (ni? me)]

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

Comment 11

[Tymur Boiko]

Please see an updated commit

Comment 12

[Tymur Boiko]

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

Comment 13

[Pulsebot]

Pushed by [e-mail]:
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

Comment 14

[Cosmin Sabou [:CosminS]]

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

Comment 15

[BMO Github Automation]

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