Google Git
Sign in
dawn / dawn / 6cbe0154290f124cf26ecc9627f4998f38c97f7c
commit6cbe0154290f124cf26ecc9627f4998f38c97f7c[log] [tgz]
authorSunny Sachanandani <sunnyps@chromium.org>Mon Jul 18 22:04:52 2022 +0000
committerDawn LUCI CQ <dawn-scoped@luci-project-accounts.iam.gserviceaccount.com>Mon Jul 18 22:04:52 2022 +0000
tree78dfa90e9523f023e087496855816a06970bbb2f
parent4a92a3c904d6a4ce477b077281ce178305f551c1 [diff]
d3d12: Fix fence signal race when no command lists are submitted

Signaling a fence in Dawn without waiting can cause a race between Dawn
and Chromium over who signals the fence. Since D3D12 fences are allowed
to be rewound this can cause future waits to hang indefinitely if Dawn
loses the race and signals a lower value than what Chromium expects.

The signal without wait case happens when Dawn submits no command lists
e.g. when CopyExternalImageToTexture uses a zero-sized dimension. This
is the reason for the test failures in https://crrev.com/c/3700811 e.g.
https://ci.chromium.org/ui/p/chromium/builders/try/dawn-win10-x64-deps-rel/24617/overview

To fix the race, it's sufficient to wait before signaling if not already
waited which is what this CL does. This CL also makes the fence stay
alive until pending signals are done - this wasn't the root cause of the
hang described above, but it's still a good idea for robustness, and
also recommended based on discussion around past Chromium XR fence use.

Bug: dawn:576
Change-Id: I8c1d1a19fdb022ae28d26f6723c2f2bfc9c1c3c7
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/96321
Auto-Submit: Sunny Sachanandani <sunnyps@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Sunny Sachanandani <sunnyps@chromium.org>
2 files changed
tree: 78dfa90e9523f023e087496855816a06970bbb2f
  1. .vscode/
  2. build_overrides/
  3. docs/
  4. generator/
  5. include/
  6. infra/
  7. scripts/
  8. src/
  9. test/
  10. third_party/
  11. tools/
  12. webgpu-cts/
  13. .clang-format
  14. .clang-tidy
  15. .gitattributes
  16. .gitignore
  17. .gn
  18. AUTHORS
  19. BUILD.gn
  20. CMakeLists.txt
  21. CMakeSettings.json
  22. CODE_OF_CONDUCT.md
  23. codereview.settings
  24. CONTRIBUTING.md
  25. CPPLINT.cfg
  26. dawn.json
  27. dawn_wire.json
  28. DEPS
  29. DIR_METADATA
  30. Doxyfile
  31. go.mod
  32. go.sum
  33. LICENSE
  34. OWNERS
  35. PRESUBMIT.py
  36. README.chromium
  37. README.md
  38. tint_overrides_with_defaults.gni
README.md

Dawn's logo: a sun rising behind a stylized mountain inspired by the WebGPU logo. The text Dawn is written below it.

Dawn, a WebGPU implementation

Dawn is an open-source and cross-platform implementation of the work-in-progress WebGPU standard. More precisely it implements webgpu.h that is a one-to-one mapping with the WebGPU IDL. Dawn is meant to be integrated as part of a larger system and is the underlying implementation of WebGPU in Chromium.

Dawn provides several WebGPU building blocks:

  • WebGPU C/C++ headers that applications and other building blocks use.
    • The webgpu.h version that Dawn implements.
    • A C++ wrapper for the webgpu.h.
  • A “native” implementation of WebGPU using platforms' GPU APIs:
    • D3D12 on Windows 10
    • Metal on macOS and iOS
    • Vulkan on Windows, Linux, ChromeOS, Android and Fuchsia
    • OpenGL as best effort where available
  • A client-server implementation of WebGPU for applications that are in a sandbox without access to native drivers
  • Tint is a compiler for the WebGPU Shader Language (WGSL).

Helpful links:

Documentation table of content

Developer documentation:

User documentation: (TODO, figure out what overlaps with the webgpu.h docs)

Status

(TODO)

License

Apache 2.0 Public License, please see LICENSE.

Disclaimer

This is not an officially supported Google product.