Mus: Compositing and Input

Kirkland, 2017/04/25

What's Mus Anyway?

• Part of the Servicification effort
• The Mojo UI Service
  • Arbitrary embedding tree
  • Centralized input dispatching
  • Centralized compositing and rasterization
  • First class OOPIF support
  • 'Cause Speed

Aside: What's Servicification?

• Servicification is “the migration from monolithic legacy applications into service-based components” https://en.wiktionary.org/wiki/servicification
• In other words: splitting a monolithic Chrome browser up into components.
• Mojo is fancy IPC to glue the components together
• Why do this?
• To further deliver on the Chrome promise:
  • Speed
  • Simplicity
  • Security
  • Stability

Servicified Chrome

Aside: Naming

• Mus is divided into two cooperating services
• services/ui aka the window server
  • Window embedding tree
  • Event targeting
  • Event dispatching
• services/viz aka the mus gpu process
  • Compositing
  • Rasterization
  • Display management
  • Hit testing support

Centralized Event Dispatching

Centralized Graphics

First Class OOPIFs

Mus Roadmap

• Mushrome:
  • Separate WS, VIZ processes
  • Mojo gpu service, compositor interface
  • (Begin?) Relocating the Display Compositor
• Tadpole/Mus+Ash:
  • separate Ash
  • Relocated the Display Compositor to VIZ
  • Begin relocating rasterization to VIZ
• Salamander:
  • Rasterization centralized in VIZ
  • Centralized Layer Compositor in VIZ
  • Central graphics scheduling

Chrome Now

Mushrome

Process Separation Forces Improvements

• CompositorFrame transport:
  • Chrome UI submits CFs via call
  • but Mushrome UI submits CFs via IPC
  • Mitigate with improved CF transport
  • Side benefit: improved renderer performance
• Event targeting using cached information:
  • DelegatedFrameHost directly interrogates surface data for event targeting
  • but surface data now only in VIZ
  • Mitigate with event targeting data sourced from blink
  • Side benefit: corrects for layer squashing targeting errors

Tadpole

Inside VIZ

Direct Compositing and Vulkan!

After Tadpole: Central Compositor

Salamander

Summary

• Part of the Servicification effort
• Tadpole
  • Centralizes DisplayCompositor
  • Enables direct rendering: Vulkan
  • Improves OOPIF support
• GPU Raster: Direct GL or Vulkan
• Salamander
  • Centralized LayerCompositor
  • Global raster occlusion
  • Efficient OOPIF support
  • Single graphics scheduling point