Zero-Copy Display of Guest Framebuffers Using GEM

Explore an advanced technique for optimizing guest video display in virtualized environments. Learn about zero-copy display of guest framebuffers using GEM (Graphics Execution Manager) in this 17-minute conference talk. Dive into the current state-of-the-art methods for displaying guest video, including their limitations and performance impacts. Discover how leveraging the DRM (Direct Rendering Manager) subsystem in dom0 on systems with unified memory architecture can significantly improve system performance and reduce power consumption. Gain insights into making arbitrary pages available for direct scanout by graphics hardware using in-kernel graphics drivers. Follow the presentation's journey from explaining the current display path to demonstrating how DRM can enhance it. Understand concepts such as dirty page tracking, QEMU graphics, foreign pages, grants, and foreign-backed GEM objects. Ideal for developers and system administrators working with virtualization technologies, particularly those interested in optimizing graphics performance in Xen environments.

Intro
Agenda
Overview of QEMU Graphics (The quick version)
Worst Case Scenario
Existing Optimizations
The Obvious Solution!
Unpleasant Reality
Foreign pages?
Grants?
Manual m2p_override
Foreign-backed GEM Objects
Code