Open Bug 1527123 Opened 5 years ago Updated 2 years ago

Add telemetry to get an idea for how often dynamic reflow roots are used in the wild

Categories

(Core :: Layout, enhancement, P3)

Product:
Core
Component:
Layout
Type:
enhancement

Tracking

()

Tracking Flags:
Tracking Status
firefox67 --- affected

People

(Reporter: dholbert, Unassigned)

References

Details

Dynamic Reflow Roots are potentially a big optimization, but they're only activated for certain very restricted scenarios (see conditions in ReflowInput::InitDynamicReflowRoot)

It'd be nice to gather some telemetry on how often they actually get used, and what sort of benefit they give.

Possible data we might want to gather:

  • number of document loads where some frame is tagged as a dynamic reflow root.

  • average depth of dynamic reflow root in the frame tree (distance to actual frametree root) -- this gives us a rough idea of how much the dynamic reflow root is buying us.

(Once we've preffed on CSS containment, we may want to gather the same sort of telemetry there as well, for containment-triggered reflow roots, per bug 1497414.)

Severity: normal → S3
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