Control timeline semaphore emulation at runtime, remove extension layer.
* The `VK_LAYER_KHRONOS_timeline_semaphore` extension layer may still be used, but it is no longer required. To simplify maintenance, this change removes IREE's build system helpers and documentation for it.
* The `integrations/tensorflow/e2e/e2e_control_flow_test_tf_iree_vulkan` test required bumping `kMaxInFlightFenceCount` to remain passing when using IREE's new timeline semaphore emulation.
* Updated SwiftShader instructions on Windows now that the Linux-only extension layer is not required with it.
diff --git a/docs/GetStarted/getting_started_linux_vulkan.md b/docs/GetStarted/getting_started_linux_vulkan.md
index 924f123..9ee8c61 100644
--- a/docs/GetStarted/getting_started_linux_vulkan.md
+++ b/docs/GetStarted/getting_started_linux_vulkan.md
@@ -24,11 +24,9 @@
using [SwiftShader](https://swiftshader.googlesource.com/SwiftShader/) (a high
performance CPU-based implementation of Vulkan).
-Vulkan API version > 1.2 is recommended where available. The
-`VK_KHR_timeline_semaphore` extension (part of Vulkan 1.2) is required, and the
-[Vulkan-ExtensionLayer](https://github.com/KhronosGroup/Vulkan-ExtensionLayer)
-project can be used to enable it for drivers (like SwiftShader) without native
-support.
+Vulkan drivers implementing API version >= 1.2 are recommended. IREE requires
+the `VK_KHR_timeline_semaphore` extension (part of Vulkan 1.2), though it is
+able to emulate it, with performance costs, as necessary.
## Vulkan Setup
@@ -97,39 +95,6 @@
$ export VK_ICD_FILENAMES=$PWD/build-swiftshader/Linux/vk_swiftshader_icd.json
```
-### Setting up Vulkan-ExtensionLayer
-
-If you are missing support for `VK_KHR_timeline_semaphore`, setup the extension
-layer.
-
-Build:
-
-```shell
-# -- CMake --
-$ cmake --build build/ --target vk_layer_khronos_timeline_semaphore
-
-# -- Bazel --
-$ bazel build @vulkan_extensionlayer//:libVkLayer_khronos_timeline_semaphore.so @vulkan_extensionlayer//:VkLayer_khronos_timeline_semaphore_json
-```
-
-You should then also set the `VK_LAYER_PATH` environment variable to include the
-path to the built layer:
-
-```shell
-# -- CMake --
-$ export VK_LAYER_PATH=$PWD/build/third_party/vulkan_extensionlayer/layers/:$VK_LAYER_PATH
-
-# -- Bazel --
-$ export VK_LAYER_PATH=$PWD/bazel-bin/external/vulkan_extensionlayer/:$VK_LAYER_PATH
-```
-
-### Setting up the Vulkan Loader
-
-IREE relies on the `VK_KHR_timeline_semaphore` extension. The minimal loader
-version supporting this extenion is `1.1.124`. So if you see failures regarding
-timeline semaphore, in addtion to setting up the extension layer, please also
-check to make sure the loader is at a proper version.
-
### Support in Bazel Tests
Bazel tests run in a sandbox, which environment variables may be forwarded to
@@ -140,7 +105,6 @@
test --test_env="LD_LIBRARY_PATH={PATH_TO_VULKAN_SDK}/x86_64/lib/"
test --test_env="LD_PRELOAD=libvulkan.so.1"
test --test_env="VK_ICD_FILENAMES={PATH_TO_IREE}/build-swiftshader/Linux/vk_swiftshader_icd.json"
-test --test_env="VK_LAYER_PATH=$VK_LAYER_PATH:{PATH_TO_IREE}/bazel-bin/external/vulkan_extensionlayer/"
```
## Using IREE's Vulkan Compiler Target and Runtime Driver
@@ -187,9 +151,3 @@
# -- Bazel --
$ bazel run iree/samples/vulkan:vulkan_inference_gui
```
-
-## What's next?
-
-More documentation coming soon...
-
-<!-- TODO(scotttodd): link to Vulkan debugging, developer guides -->
