mirror of
https://github.com/status-im/Vulkan-Docs.git
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82e0f83d43
* Bump API patch number and header version number to 40 for this update.
* There is a major build change in this release. We are now using the
Ruby-based ``asciidoctor'' implementation, rather than the Python-based
``asciidoc'' implementation, to process the specification. While the
actual specification markup changes were minimal, this requires a new
set of build tools and a very different installation process, especially
because we now use an experimental direct-to-PDF backend for Asciidoctor
instead of Docbook->dblatex->PDF. It is no longer possible to build the
Specification using asciidoc. See doc/specs/vulkan/README.adoc
for some guidance on installing the new toolchain components.
* There are some minor rendering issues in the PDF output due to teething
problems with the asciidoctor toolchain, especially with mathematical
equations. We are aware of these and working on them.
Github Issues:
* Updated sample code for the <<sparsememory-examples-basic,sparse
resource binding example>> (public issue 97).
* Modify line and point clipping behavior in the
<<vertexpostproc-clipping, Primitive Clipping>> section to allow for
pop-free behavior. The ability to check for which behavior is
implemented may be added a future feature or extension (public issue
113).
* Unify the discussions of implicit ordering throughout the spec, in
particular in the new sections <<drawing-primitive-order, Primitive
Order>>, <<primrast-order, Rasterization Order>>, and
<<synchronization-implicit, Implicit Synchronization Guarantees>>; the
discussion of <<synchronization-submission-order, submission order>>;
and references elsewhere to these sections (public issue 133).
* Clarify \<\<descriptorsets-compatibility,Pipeline Layout Compatibility>>
language and introduce the term ``identically defined'' (public issue
164).
* Add a dependency to the +VK_EXT_debug_marker+ extension that's needed to
reuse the object type enum from +VK_EXT_debug_report+, and moves the
definition of that enum into +VK_EXT_debug_report+ where it should be
(public issue 409).
* Remove redundant valid usage statement from slink:VkImageBlit (public
issue 421).
* Update GL_KHR_vulkan_glsl to allow the ternary operator to result in a
specialization constant (public issue 424).
* Fix valid usage for flink:VkPipelineShaderStageCreateInfo (public issue
426).
* Correct typo in New Objects list for <<VK_EXT_debug_report>> (public
issue 447).
Internal Issues:
* Moved to asciidoctor for spec builds (internal issue 121).
* Update style guide to describe where to put new extensions-specific
asciidoc files, and what to name them (internal issue 626).
* Add src/spec/indexExt.py to autogenerate registry index entries linking
into the 1.0-extensions specification, instead of maintaining the index
manually. (internal issue 642).
* Autogenerate extension dependencies and lists of all extensions and all
KHR extensions from the "supported" attributes in +vk.xml+. Execute
+make config/extDependency.sh+ from +doc/specs/vulkan+ when a supported
extension is added to vk.xml, to regenerate the dependency script. The
consequence is that specifying a single extension to the +makeExt+
script will automatically enable all extensions it depends on as well,
and that the +makeAllExts+ and +makeKHR+ scripts do not need to be
updated when a new extension is supported (internal issue 648).
* Put extension appendices all at the same asciidoc section level, so KHR
WSI extensions show up in the HTML index (internal issue 648).
Other Issues:
* Imbed images in the generated HTML specs instead of loading them from
the images/ directory.
* Fix missing EXT in extension name
(ename:VK_EXT_SWAPCHAIN_COLOR_SPACE_EXTENSION_NAME).
* Add new +VK_EXT_SMPTE_2086_metadata+ extension.
* In the <<platformCreateSurface_xlib,Xlib Surface>> section of the
+VK_KHR_xlib_surface+ specification, add language warning users that
they always need to call code:XinitThreads.
* Use the term "presentable image" (rather than "swapchain image")
consistently in +VK_KHR_swapchain+ and related extensions, and add a
glossary term defining it.
* Relocate the valid usage for samples of
flink:vkGetPhysicalDeviceSparseImageFormatProperties2KHR::pname:pFormatInfo
to be below the flink:VkPhysicalDeviceSparseImageFormatInfo2KHR
structure.
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// Copyright (c) 2015-2017 The Khronos Group Inc.
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// Copyright notice at https://www.khronos.org/registry/speccopyright.html
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[[synchronization]]
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= Synchronization and Cache Control
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Synchronization of access to resources is primarily the responsibility of
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the application in Vulkan.
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The order of execution of commands with respect to the host and other
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commands on the device has few implicit guarantees, and needs to be
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explicitly specified.
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Memory caches and other optimizations are also explicitly managed, requiring
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that the flow of data through the system is largely under application
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control.
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Whilst some implicit guarantees exist between commands, four explicit
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synchronization primitives are exposed by Vulkan:
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<<synchronization-fences,Fences>>::
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Fences can: be used to communicate to the host that execution of some
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task on the device has completed.
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<<synchronization-semaphores,Semaphores>>::
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Semaphores can: be used to control resource access across multiple
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queues.
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<<synchronization-events,Events>>::
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Events provide a fine-grained synchronization primitive which can: be
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signaled either within a command buffer or by the host, and can: be
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waited upon within a command buffer or queried on the host.
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<<synchronization-pipeline-barriers,Pipeline Barriers>>::
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Pipeline barriers also provide synchronization control within a command
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buffer, but at a single point, rather than with separate signal and wait
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operations.
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In addition to the base primitives provided here, <<renderpass, Render
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Passes>> provide a useful synchronization framework for most rendering
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tasks, built upon the concepts in this chapter.
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Many cases that would otherwise need an application to use synchronization
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primitives in this chapter can: be expressed more efficiently as part of a
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render pass.
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[[synchronization-dependencies]]
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== Execution and Memory Dependencies
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An _operation_ is an arbitrary amount of work to be executed on the host, a
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device, or an external entity such as a presentation engine.
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Synchronization commands introduce explicit _execution dependencies_, and
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_memory dependencies_ between two sets of operations defined by the
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command's two _synchronization scopes_.
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[[synchronization-dependencies-scopes]]
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The synchronization scopes define which other operations a synchronization
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command is able to create execution dependencies with.
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Any type of operation that is not in a synchronization command's
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synchronization scopes will not be included in the resulting dependency.
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For example, for many synchronization commands, the synchronization scopes
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can: be limited to just operations executing in specific
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<<synchronization-pipeline-stages,pipeline stages>>, which allows other
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pipeline stages to be excluded from a dependency.
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Other scoping options are possible, depending on the particular command.
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[[synchronization-dependencies-execution]]
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An _execution dependency_ is a guarantee that for two sets of operations,
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the first set must: _happen-before_ the second set.
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If an operation happens-before another operation, then the first operation
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must: complete before the second operation is initiated.
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More precisely:
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* Let *A* and *B* be separate sets of operations.
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* Let *S* be a synchronization command.
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* Let *A~S~* and *B~S~* be the synchronization scopes of *S*.
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* Let *A'* be the intersection of sets *A* and *A~S~*.
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* Let *B'* be the intersection of sets *B* and *B~S~*.
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* Submitting *A*, *S* and *B* for execution, in that order, will result in
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execution dependency *E* between *A'* and *B'*.
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* Execution dependency *E* guarantees that *A'* happens-before *B'*.
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[[synchronization-dependencies-chains]]
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An _execution dependency chain_ is a sequence of execution dependencies that
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form a happens-before relation between the first dependency's *A'* and the
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final dependency's *B'*.
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For each consecutive pair of execution dependencies, a chain exists if the
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intersection of *B~S~* in the first dependency and *A~S~* in the second
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dependency is not an empty set.
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The formation of a single execution dependency from an execution dependency
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chain can be described by substituting the following in the description of
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execution dependencies:
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* Let *S* be a set of synchronization commands that generate an execution
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dependency chain.
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* Let *A~S~* be the first synchronization scope of the first command in
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*S*.
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* Let *B~S~* be the second synchronization scope of the last command in
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*S*.
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.Note
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[NOTE]
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====
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An execution dependency is inherently also multiple execution dependencies -
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a dependency exists between each subset of *A'* and each subset of *B'*, and
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the same is true for execution dependency chains.
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For example, a synchronization command with multiple
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<<synchronization-pipeline-stages,pipeline stages>> in its stage masks
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effectively generates one dependency between each source stage and each
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destination stage.
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This can be useful to think about when considering how execution chains are
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formed if they don't involve all parts of a synchronization command's
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dependency.
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Similarly, any set of adjacent dependencies in an execution dependency chain
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can: be considered an execution dependency chain in its own right.
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====
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Execution dependencies alone are not sufficient to guarantee that values
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resulting from writes in one set of operations can: be read from another set
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of operations.
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[[synchronization-dependencies-available-and-visible]]
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Two additional types of operation are used to control memory access.
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_Availability operations_ cause the values generated by specified memory
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write accesses to become _available_ for future access.
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Any available value remains available until a subsequent write to the same
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memory location occurs (whether it is made available or not) or the memory
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is freed.
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_Visibility operations_ cause any available values to become _visible_ to
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specified memory accesses.
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[[synchronization-dependencies-memory]]
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A _memory dependency_ is an execution dependency which includes availability
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and visibility operations such that:
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* The first set of operations happens-before the availability operation.
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* The availability operation happens-before the visibility operation.
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* The visibility operation happens-before the second set of operations.
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Once written values are made visible to a particular type of memory access,
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they can: be read or written by that type of memory access.
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Most synchronization commands in Vulkan define a memory dependency.
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[[synchronization-dependencies-access-scopes]]
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The specific memory accesses that are made available and visible are defined
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by the _access scopes_ of a memory dependency.
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Any type of access that is in a memory dependency's first access scope and
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occurs in *A'* is made available.
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Any type of access that is in a memory dependency's second access scope and
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occurs in *B'* has any available writes made visible to it.
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Any type of operation that is not in a synchronization command's access
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scopes will not be included in the resulting dependency.
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A memory dependency enforces availability and visibility of memory accesses
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and execution order between two sets of operations.
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Adding to the description of <<synchronization-dependencies-chains,
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execution dependency chains>>:
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* Let *a* be the set of memory accesses performed by *A'*.
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* Let *b* be the set of memory accesses performed by *B'*.
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* Let *a~S~* be the first access scope of the first command in *S*.
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* Let *b~S~* be the second access scope of the last command in *S*.
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* Let *a'* be the intersection of sets *a* and *a~S~*.
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* Let *b'* be the intersection of sets *b* and *b~S~*.
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* Submitting *A*, *S* and *B* for execution, in that order, will result in
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a memory dependency *m* between *A'* and *B'*.
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* Memory dependency *m* guarantees that:
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** Memory writes in *a'* are made available.
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** Available memory writes, including those from *a'*, are made visible to
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*b'*.
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[NOTE]
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.Note
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====
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Execution and memory dependencies are used to solve data hazards, i.e. to
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ensure that read and write operations occur in a well-defined order.
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Write-after-read hazards can be solved with just an execution dependency,
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but read-after-write and write-after-write hazards need appropriate memory
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dependencies to be included between them.
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If an application does not include dependencies to solve these hazards, the
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results and execution orders of memory accesses are undefined.
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====
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[[synchronization-image-layout-transitions]]
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=== Image Layout Transitions
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Image subresources can: be transitioned from one <<resources-image-layouts,
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layout>> to another as part of a <<synchronization-dependencies-memory,
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memory dependency>> (e.g. by using an
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<<synchronization-image-memory-barriers,image memory barrier>>).
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When a layout transition is specified in a memory dependency, it
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happens-after the availability operations in the memory dependency, and
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happens-before the visibility operations.
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Image layout transitions may: perform read and write accesses on all memory
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bound to the image subresource range, so applications must: ensure that all
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memory writes have been made
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<<synchronization-dependencies-available-and-visible, available>> before a
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layout transition is executed.
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Available memory is automatically made visible to a layout transition, and
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writes performed by a layout transition are automatically made available.
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Layout transitions always apply to a particular image subresource range, and
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specify both an old layout and new layout.
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If the old layout does not match the new layout, a transition occurs.
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The old layout must: match the current layout of the image subresource
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range, with one exception.
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The old layout can: always be specified as ename:VK_IMAGE_LAYOUT_UNDEFINED,
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though doing so invalidates the contents of the image subresource range.
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.Note
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[NOTE]
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====
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Setting the old layout to ename:VK_IMAGE_LAYOUT_UNDEFINED implies that the
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contents of the image subresource need not be preserved.
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Implementations may: use this information to avoid performing expensive data
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transition operations.
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====
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.Note
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[NOTE]
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====
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Applications must: ensure that layout transitions happen-after all
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operations accessing the image with the old layout, and happen-before any
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operations that will access the image with the new layout.
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Layout transitions are potentially read/write operations, so not defining
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appropriate memory dependencies to guarantee this will result in a data
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race.
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====
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The contents of any portion of another resource which aliases memory that is
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bound to the transitioned image subresource range are undefined after an
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image layout transition.
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[[synchronization-pipeline-stages]]
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=== Pipeline Stages
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The work performed by an <<fundamentals-queueoperation-command-types, action
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command>> consists of multiple operations, which are performed by a sequence
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of logically independent execution units known as _pipeline stages_.
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The exact pipeline stages executed depend on the particular action command
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that is used, and current command buffer state when the action command was
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recorded.
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<<drawing,Drawing commands>>, <<dispatch,dispatching commands>>,
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<<copies,copy commands>>, and <<clears,clear commands>> all execute in
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different sets of <<synchronization-pipeline-stages-types,pipeline stages>>.
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Execution of operations across pipeline stages must: adhere to
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<<synchronization-implicit, implicit ordering guarantees>>, particularly
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including <<synchronization-pipeline-stages-order, pipeline stage order>>.
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Otherwise, execution across pipeline stages may: overlap or execute out of
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order with regards to other stages, unless otherwise enforced by an
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execution dependency.
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// refBegin VkPipelineStageFlagBits - Bitmask specifying pipeline stages
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Several of the synchronization commands include pipeline stage parameters,
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restricting the <<synchronization-dependencies-scopes, synchronization
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scopes>> for that command to just those stages.
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This allows fine grained control over the exact execution dependencies and
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accesses performed by action commands.
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Implementations should: use these pipeline stages to avoid unnecessary
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stalls or cache flushing.
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Pipeline stages are specified using a bitmask:
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include::../api/enums/VkPipelineStageFlagBits.txt[]
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The meaning of each bit is:
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* ename:VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT: Stage of the pipeline where any
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commands are initially received by the queue.
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ifdef::VK_NVX_device_generated_commands[]
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* ename:VK_PIPELINE_STAGE_COMMAND_PROCESS_BIT_NVX: Stage of the pipeline
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where device-side generation of commands via
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flink:vkCmdProcessCommandsNVX is handled.
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endif::VK_NVX_device_generated_commands[]
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* ename:VK_PIPELINE_STAGE_DRAW_INDIRECT_BIT: Stage of the pipeline where
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Draw/DispatchIndirect data structures are consumed.
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ifdef::VK_NVX_device_generated_commands[]
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This stage also includes reading commands written by
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flink:vkCmdProcessCommandsNVX.
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endif::VK_NVX_device_generated_commands[]
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* ename:VK_PIPELINE_STAGE_VERTEX_INPUT_BIT: Stage of the pipeline where
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vertex and index buffers are consumed.
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* ename:VK_PIPELINE_STAGE_VERTEX_SHADER_BIT: Vertex shader stage.
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* ename:VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT: Tessellation
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control shader stage.
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* ename:VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT: Tessellation
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evaluation shader stage.
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* ename:VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT: Geometry shader stage.
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* ename:VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT: Fragment shader stage.
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* ename:VK_PIPELINE_STAGE_EARLY_FRAGMENT_TESTS_BIT: Stage of the pipeline
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where early fragment tests (depth and stencil tests before fragment
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shading) are performed.
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This stage also includes <<renderpass-load-store-ops, subpass load
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operations>> for framebuffer attachments with a depth/stencil format.
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* ename:VK_PIPELINE_STAGE_LATE_FRAGMENT_TESTS_BIT: Stage of the pipeline
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where late fragment tests (depth and stencil tests after fragment
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shading) are performed.
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This stage also includes <<renderpass-load-store-ops, subpass store
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operations>> for framebuffer attachments with a depth/stencil format.
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* ename:VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT: Stage of the
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pipeline after blending where the final color values are output from the
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pipeline.
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This stage also includes <<renderpass-load-store-ops, subpass load and
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store operations>> and multisample resolve operations for framebuffer
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attachments with a color format.
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* [[synchronization-pipeline-stages-transfer]]
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ename:VK_PIPELINE_STAGE_TRANSFER_BIT: Execution of copy commands.
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This includes the operations resulting from all <<copies,copy
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commands>>, <<clears,clear commands>> (with the exception of
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flink:vkCmdClearAttachments), and flink:vkCmdCopyQueryPoolResults.
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* ename:VK_PIPELINE_STAGE_COMPUTE_SHADER_BIT: Execution of a compute
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shader.
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* ename:VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT: Final stage in the pipeline
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where operations generated by all commands complete execution.
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* ename:VK_PIPELINE_STAGE_HOST_BIT: A pseudo-stage indicating execution on
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the host of reads/writes of device memory.
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This stage is not invoked by any commands recorded in a command buffer.
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* ename:VK_PIPELINE_STAGE_ALL_GRAPHICS_BIT: Execution of all graphics
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pipeline stages.
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Equivalent to the logical or of:
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** ename:VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT
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** ename:VK_PIPELINE_STAGE_DRAW_INDIRECT_BIT
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** ename:VK_PIPELINE_STAGE_VERTEX_INPUT_BIT
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** ename:VK_PIPELINE_STAGE_VERTEX_SHADER_BIT
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** ename:VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT
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** ename:VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT
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** ename:VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT
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** ename:VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT
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** ename:VK_PIPELINE_STAGE_EARLY_FRAGMENT_TESTS_BIT
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** ename:VK_PIPELINE_STAGE_LATE_FRAGMENT_TESTS_BIT
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** ename:VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT
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** ename:VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT
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* ename:VK_PIPELINE_STAGE_ALL_COMMANDS_BIT: Equivalent to the logical or
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of every other pipeline stage flag that is supported on the queue it is
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used with.
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[NOTE]
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.Note
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====
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An execution dependency with only ename:VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT
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in the destination stage mask will only prevent that stage from executing in
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subsequently submitted commands.
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As this stage doesn't perform any actual execution, this is not observable -
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in effect, it does not delay processing of subsequent commands.
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Similarly an execution dependency with only
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ename:VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT in the source stage mask will
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effectively not wait for any prior commands to complete.
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When defining a memory dependency, using only
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ename:VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT or
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ename:VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT would never make any accesses
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available and/or visible because these stages do not access memory.
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ename:VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT and
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ename:VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT are useful for accomplishing layout
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transitions and queue ownership operations when the required execution
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dependency is satisfied by other means - for example, semaphore operations
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between queues.
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====
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// refEnd VkPipelineStageFlagBits
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|
|
[[synchronization-pipeline-stages-masks]]
|
|
If a synchronization command includes a source stage mask, its first
|
|
<<synchronization-dependencies-scopes, synchronization scope>> only includes
|
|
execution of the pipeline stages specified in that mask, as well as any
|
|
<<synchronization-pipeline-stages-order, logically earlier>> stages.
|
|
If a synchronization command includes a destination stage mask, its second
|
|
<<synchronization-dependencies-scopes, synchronization scope>> only includes
|
|
execution of the pipeline stages specified in that mask, as well as any
|
|
<<synchronization-pipeline-stages-order, logically later>> stages.
|
|
|
|
<<synchronization-dependencies-access-scopes, Access scopes>> are affected
|
|
in a similar way.
|
|
If a synchronization command includes a source stage mask, its first
|
|
<<synchronization-dependencies-access-scopes, access scope>> only includes
|
|
memory access performed by pipeline stages specified in that mask.
|
|
If a synchronization command includes a destination stage mask, its second
|
|
<<synchronization-dependencies-access-scopes, access scope>> only includes
|
|
memory access performed by pipeline stages specified in that mask.
|
|
|
|
[NOTE]
|
|
.Note
|
|
====
|
|
Implementations may: not support synchronization at every pipeline stage for
|
|
every synchronization operation.
|
|
If a pipeline stage that an implementation does not support synchronization
|
|
for appears in a source stage mask, then it may: substitute that stage for
|
|
any logically later stage.
|
|
If a pipeline stage that an implementation does not support synchronization
|
|
for appears in a destination stage mask, then it may: substitute that stage
|
|
for any logically earlier stage.
|
|
|
|
For example, if an implementation is unable to signal an event immediately
|
|
after vertex shader execution is complete, it may: instead signal the event
|
|
after color attachment output has completed.
|
|
|
|
If an implementation makes such a substitution, it must: not affect the
|
|
semantics of execution or memory dependencies or image and buffer memory
|
|
barriers.
|
|
====
|
|
|
|
Certain pipeline stages are only available on queues that support a
|
|
particular set of operations.
|
|
The following table lists, for each pipeline stage flag, which queue
|
|
capability flag must: be supported by the queue.
|
|
When multiple flags are enumerated in the second column of the table, it
|
|
means that the pipeline stage is supported on the queue if it supports any
|
|
of the listed capability flags.
|
|
For further details on queue capabilities see
|
|
<<devsandqueues-physical-device-enumeration,Physical Device Enumeration>>
|
|
and <<devsandqueues-queues,Queues>>.
|
|
|
|
[[synchronization-pipeline-stages-supported]]
|
|
.Supported pipeline stage flags
|
|
[cols="60%,40%",options="header"]
|
|
|====
|
|
|Pipeline stage flag | Required queue capability flag
|
|
|ename:VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT | None required
|
|
|ename:VK_PIPELINE_STAGE_DRAW_INDIRECT_BIT | ename:VK_QUEUE_GRAPHICS_BIT or ename:VK_QUEUE_COMPUTE_BIT
|
|
|ename:VK_PIPELINE_STAGE_VERTEX_INPUT_BIT | ename:VK_QUEUE_GRAPHICS_BIT
|
|
|ename:VK_PIPELINE_STAGE_VERTEX_SHADER_BIT | ename:VK_QUEUE_GRAPHICS_BIT
|
|
|ename:VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT | ename:VK_QUEUE_GRAPHICS_BIT
|
|
|ename:VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT | ename:VK_QUEUE_GRAPHICS_BIT
|
|
|ename:VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT | ename:VK_QUEUE_GRAPHICS_BIT
|
|
|ename:VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT | ename:VK_QUEUE_GRAPHICS_BIT
|
|
|ename:VK_PIPELINE_STAGE_EARLY_FRAGMENT_TESTS_BIT | ename:VK_QUEUE_GRAPHICS_BIT
|
|
|ename:VK_PIPELINE_STAGE_LATE_FRAGMENT_TESTS_BIT | ename:VK_QUEUE_GRAPHICS_BIT
|
|
|ename:VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT | ename:VK_QUEUE_GRAPHICS_BIT
|
|
|ename:VK_PIPELINE_STAGE_COMPUTE_SHADER_BIT | ename:VK_QUEUE_COMPUTE_BIT
|
|
|ename:VK_PIPELINE_STAGE_TRANSFER_BIT | ename:VK_QUEUE_GRAPHICS_BIT, ename:VK_QUEUE_COMPUTE_BIT or ename:VK_QUEUE_TRANSFER_BIT
|
|
|ename:VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT | None required
|
|
|ename:VK_PIPELINE_STAGE_HOST_BIT | None required
|
|
|ename:VK_PIPELINE_STAGE_ALL_GRAPHICS_BIT | ename:VK_QUEUE_GRAPHICS_BIT
|
|
|ename:VK_PIPELINE_STAGE_ALL_COMMANDS_BIT | None required
|
|
ifdef::VK_NVX_device_generated_commands[]
|
|
|ename:VK_PIPELINE_STAGE_COMMAND_PROCESS_BIT_NVX | ename:VK_QUEUE_GRAPHICS_BIT or ename:VK_QUEUE_COMPUTE_BIT
|
|
endif::VK_NVX_device_generated_commands[]
|
|
|====
|
|
|
|
[[synchronization-pipeline-stages-order]]
|
|
Pipeline stages that execute as a result of a command logically complete
|
|
execution in a specific order, such that completion of a logically later
|
|
pipeline stage must: not happen-before completion of a logically earlier
|
|
stage.
|
|
This means that including any given stage in the source stage mask for a
|
|
particular synchronization command also implies that any logically earlier
|
|
stages are included in *A~S~* for that command.
|
|
|
|
Similarly, initiation of a logically earlier pipeline stage must: not
|
|
happen-after initiation of a logically later pipeline stage.
|
|
Including any given stage in the destination stage mask for a particular
|
|
synchronization command also implies that any logically later stages are
|
|
included in *B~S~* for that command.
|
|
|
|
.Note
|
|
[NOTE]
|
|
====
|
|
Logically earlier/later stages are not included when defining the
|
|
<<synchronization-dependencies-access-scopes, access scopes>> of a
|
|
<<synchronization-memory-barriers,memory barrier>>.
|
|
====
|
|
|
|
[[synchronization-pipeline-stages-types]]
|
|
The order of pipeline stages depends on the particular pipeline; graphics,
|
|
compute, transfer or host.
|
|
|
|
For the graphics pipeline, the following stages occur in this order:
|
|
|
|
* ename:VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT
|
|
* ename:VK_PIPELINE_STAGE_DRAW_INDIRECT_BIT
|
|
* ename:VK_PIPELINE_STAGE_VERTEX_INPUT_BIT
|
|
* ename:VK_PIPELINE_STAGE_VERTEX_SHADER_BIT
|
|
* ename:VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT
|
|
* ename:VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT
|
|
* ename:VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT
|
|
* ename:VK_PIPELINE_STAGE_EARLY_FRAGMENT_TESTS_BIT
|
|
* ename:VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT
|
|
* ename:VK_PIPELINE_STAGE_LATE_FRAGMENT_TESTS_BIT
|
|
* ename:VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT
|
|
* ename:VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT
|
|
|
|
For the compute pipeline, the following stages occur in this order:
|
|
|
|
* ename:VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT
|
|
* ename:VK_PIPELINE_STAGE_DRAW_INDIRECT_BIT
|
|
* ename:VK_PIPELINE_STAGE_COMPUTE_SHADER_BIT
|
|
* ename:VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT
|
|
|
|
For the transfer pipeline, the following stages occur in this order:
|
|
|
|
* ename:VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT
|
|
* ename:VK_PIPELINE_STAGE_TRANSFER_BIT
|
|
* ename:VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT
|
|
|
|
For host operations, only one pipeline stage occurs, so no order is
|
|
guaranteed:
|
|
|
|
* ename:VK_PIPELINE_STAGE_HOST_BIT
|
|
|
|
ifdef::VK_NVX_device_generated_commands[]
|
|
For the command processing pipeline, the following stages occur in this
|
|
order:
|
|
|
|
* ename:VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT
|
|
* ename:VK_PIPELINE_STAGE_COMMAND_PROCESS_BIT_NVX
|
|
* ename:VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT
|
|
endif::VK_NVX_device_generated_commands[]
|
|
|
|
[[synchronization-access-types]]
|
|
=== Access Types
|
|
|
|
Memory in Vulkan can: be accessed from within shader invocations and via
|
|
some fixed-function stages of the pipeline.
|
|
The _access type_ is a function of the <<descriptorsets, descriptor type>>
|
|
used, or how a fixed-function stage accesses memory.
|
|
Each access type corresponds to a bit flag in slink:VkAccessFlagBits.
|
|
|
|
[[synchronization-access-masks]]
|
|
Some synchronization commands take sets of access types as parameters to
|
|
define the <<synchronization-dependencies-access-scopes, access scopes>> of
|
|
a memory dependency.
|
|
If a synchronization command includes a source access mask, its first
|
|
<<synchronization-dependencies-access-scopes, access scope>> only includes
|
|
accesses via the access types specified in that mask.
|
|
Similarly, if a synchronization command includes a destination access mask,
|
|
its second <<synchronization-dependencies-access-scopes, access scope>> only
|
|
includes accesses via the access types specified in that mask.
|
|
|
|
// refBegin VkAccessFlagBits Bitmask specifying memory access types that will participate in a memory dependency
|
|
|
|
Access types that can be set in an access mask include:
|
|
|
|
[[synchronization-access-flags]]
|
|
include::../api/enums/VkAccessFlagBits.txt[]
|
|
|
|
* ename:VK_ACCESS_INDIRECT_COMMAND_READ_BIT: Read access to an indirect
|
|
command structure read as part of an indirect drawing or dispatch
|
|
command.
|
|
* ename:VK_ACCESS_INDEX_READ_BIT: Read access to an index buffer as part
|
|
of an indexed drawing command, bound by flink:vkCmdBindIndexBuffer.
|
|
* ename:VK_ACCESS_VERTEX_ATTRIBUTE_READ_BIT: Read access to a vertex
|
|
buffer as part of a drawing command, bound by
|
|
flink:vkCmdBindVertexBuffers.
|
|
* ename:VK_ACCESS_UNIFORM_READ_BIT: Read access to a
|
|
<<descriptorsets-uniformbuffer, uniform buffer>>.
|
|
* ename:VK_ACCESS_INPUT_ATTACHMENT_READ_BIT: Read access to an
|
|
<<renderpass, input attachment>> within a renderpass during fragment
|
|
shading.
|
|
* ename:VK_ACCESS_SHADER_READ_BIT: Read access to a
|
|
<<descriptorsets-storagebuffer, storage buffer>>,
|
|
<<descriptorsets-uniformtexelbuffer, uniform texel buffer>>,
|
|
<<descriptorsets-storagetexelbuffer, storage texel buffer>>,
|
|
<<descriptorsets-sampledimage, sampled image>>, or
|
|
<<descriptorsets-storageimage, storage image>>.
|
|
* ename:VK_ACCESS_SHADER_WRITE_BIT: Write access to a
|
|
<<descriptorsets-storagebuffer, storage buffer>>,
|
|
<<descriptorsets-storagetexelbuffer, storage texel buffer>>, or
|
|
<<descriptorsets-storageimage, storage image>>.
|
|
* ename:VK_ACCESS_COLOR_ATTACHMENT_READ_BIT: Read access to a
|
|
<<renderpass, color attachment>>, such as via <<framebuffer-blending,
|
|
blending>>, <<framebuffer-logicop, logic operations>>, or via certain
|
|
<<renderpass-load-store-ops, subpass load operations>>.
|
|
* ename:VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT: Write access to a
|
|
<<renderpass, color or resolve attachment>> during a <<renderpass,
|
|
render pass>> or via certain <<renderpass-load-store-ops, subpass load
|
|
and store operations>>.
|
|
* ename:VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_READ_BIT: Read access to a
|
|
<<renderpass, depth/stencil attachment>>, via <<fragops-ds-state, depth
|
|
or stencil operations>> or via certain <<renderpass-load-store-ops,
|
|
subpass load operations>>.
|
|
* ename:VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT: Write access to a
|
|
<<renderpass, depth/stencil attachment>>, via <<fragops-ds-state, depth
|
|
or stencil operations>> or via certain <<renderpass-load-store-ops,
|
|
subpass load and store operations>>.
|
|
* ename:VK_ACCESS_TRANSFER_READ_BIT: Read access to an image or buffer in
|
|
a <<copies, copy>> operation.
|
|
* ename:VK_ACCESS_TRANSFER_WRITE_BIT: Write access to an image or buffer
|
|
in a <<clears, clear>> or <<copies, copy>> operation.
|
|
* ename:VK_ACCESS_HOST_READ_BIT: Read access by a host operation.
|
|
Accesses of this type are not performed through a resource, but directly
|
|
on memory.
|
|
* ename:VK_ACCESS_HOST_WRITE_BIT: Write access by a host operation.
|
|
Accesses of this type are not performed through a resource, but directly
|
|
on memory.
|
|
* ename:VK_ACCESS_MEMORY_READ_BIT: Read access via non-specific entities.
|
|
These entities include the Vulkan device and host, but may: also include
|
|
entities external to the Vulkan device or otherwise not part of the core
|
|
Vulkan pipeline.
|
|
When included in a destination access mask, makes all available writes
|
|
visible to all future read accesses on entities known to the Vulkan
|
|
device.
|
|
* ename:VK_ACCESS_MEMORY_WRITE_BIT: Write access via non-specific
|
|
entities.
|
|
These entities include the Vulkan device and host, but may: also include
|
|
entities external to the Vulkan device or otherwise not part of the core
|
|
Vulkan pipeline.
|
|
When included in a source access mask, all writes that are performed by
|
|
entities known to the Vulkan device are made available.
|
|
When included in a destination access mask, makes all available writes
|
|
visible to all future write accesses on entities known to the Vulkan
|
|
device.
|
|
ifdef::VK_NVX_device_generated_commands[]
|
|
* ename:VK_ACCESS_COMMAND_PROCESS_READ_BIT_NVX: Reads from sname:VkBuffer
|
|
inputs to flink:vkCmdProcessCommandsNVX.
|
|
* ename:VK_ACCESS_COMMAND_PROCESS_WRITE_BIT_NVX: Writes to the target
|
|
command buffer in flink:vkCmdProcessCommandsNVX.
|
|
endif::VK_NVX_device_generated_commands[]
|
|
|
|
Certain access types are only performed by a subset of pipeline stages.
|
|
Any synchronization command that takes both stage masks and access masks
|
|
uses both to define the <<synchronization-dependencies-access-scopes, access
|
|
scopes>> - only the specified access types performed by the specified stages
|
|
are included in the access scope.
|
|
An application must: not specify an access flag in a synchronization command
|
|
if it does not include a pipeline stage in the corresponding stage mask that
|
|
is able to perform accesses of that type.
|
|
The following table lists, for each access flag, which pipeline stages can:
|
|
perform that type of access.
|
|
|
|
[[synchronization-access-types-supported]]
|
|
.Supported access types
|
|
[cols="50,50",options="header"]
|
|
|====
|
|
|Access flag | Supported pipeline stages
|
|
|ename:VK_ACCESS_INDIRECT_COMMAND_READ_BIT | ename:VK_PIPELINE_STAGE_DRAW_INDIRECT_BIT
|
|
|ename:VK_ACCESS_INDEX_READ_BIT | ename:VK_PIPELINE_STAGE_VERTEX_INPUT_BIT
|
|
|ename:VK_ACCESS_VERTEX_ATTRIBUTE_READ_BIT | ename:VK_PIPELINE_STAGE_VERTEX_INPUT_BIT
|
|
|ename:VK_ACCESS_UNIFORM_READ_BIT | ename:VK_PIPELINE_STAGE_VERTEX_SHADER_BIT, ename:VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT, ename:VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT, ename:VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT, ename:VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT, or ename:VK_PIPELINE_STAGE_COMPUTE_SHADER_BIT
|
|
|ename:VK_ACCESS_INPUT_ATTACHMENT_READ_BIT | ename:VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT
|
|
|ename:VK_ACCESS_SHADER_READ_BIT | ename:VK_PIPELINE_STAGE_VERTEX_SHADER_BIT, ename:VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT, ename:VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT, ename:VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT, ename:VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT, or ename:VK_PIPELINE_STAGE_COMPUTE_SHADER_BIT
|
|
|ename:VK_ACCESS_SHADER_WRITE_BIT | ename:VK_PIPELINE_STAGE_VERTEX_SHADER_BIT, ename:VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT, ename:VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT, ename:VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT, ename:VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT, or ename:VK_PIPELINE_STAGE_COMPUTE_SHADER_BIT
|
|
|ename:VK_ACCESS_COLOR_ATTACHMENT_READ_BIT | ename:VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT
|
|
|ename:VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT | ename:VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT
|
|
|ename:VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_READ_BIT | ename:VK_PIPELINE_STAGE_EARLY_FRAGMENT_TESTS_BIT, or ename:VK_PIPELINE_STAGE_LATE_FRAGMENT_TESTS_BIT
|
|
|ename:VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT | ename:VK_PIPELINE_STAGE_EARLY_FRAGMENT_TESTS_BIT, or ename:VK_PIPELINE_STAGE_LATE_FRAGMENT_TESTS_BIT
|
|
|ename:VK_ACCESS_TRANSFER_READ_BIT | ename:VK_PIPELINE_STAGE_TRANSFER_BIT
|
|
|ename:VK_ACCESS_TRANSFER_WRITE_BIT | ename:VK_PIPELINE_STAGE_TRANSFER_BIT
|
|
|ename:VK_ACCESS_HOST_READ_BIT | ename:VK_PIPELINE_STAGE_HOST_BIT
|
|
|ename:VK_ACCESS_HOST_WRITE_BIT | ename:VK_PIPELINE_STAGE_HOST_BIT
|
|
|ename:VK_ACCESS_MEMORY_READ_BIT | N/A
|
|
|ename:VK_ACCESS_MEMORY_WRITE_BIT | N/A
|
|
ifdef::VK_NVX_device_generated_commands[]
|
|
|ename:VK_ACCESS_COMMAND_PROCESS_READ_BIT_NVX | ename:VK_PIPELINE_STAGE_COMMAND_PROCESS_BIT_NVX
|
|
|ename:VK_ACCESS_COMMAND_PROCESS_WRITE_BIT_NVX | ename:VK_PIPELINE_STAGE_COMMAND_PROCESS_BIT_NVX
|
|
endif::VK_NVX_device_generated_commands[]
|
|
|====
|
|
|
|
|
|
[[synchronization-framebuffer-regions]]
|
|
=== Framebuffer Region Dependencies
|
|
|
|
<<synchronization-pipeline-stages, Pipeline stages>> that operate on, or
|
|
with respect to, the framebuffer are collectively the _framebuffer-space_
|
|
pipeline stages.
|
|
These stages are:
|
|
|
|
* ename:VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT
|
|
* ename:VK_PIPELINE_STAGE_EARLY_FRAGMENT_TESTS_BIT
|
|
* ename:VK_PIPELINE_STAGE_LATE_FRAGMENT_TESTS_BIT
|
|
* ename:VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT
|
|
|
|
For these pipeline stages, an execution or memory dependency from the first
|
|
set of operations to the second set can: either be a single
|
|
_framebuffer-global_ dependency, or split into multiple _framebuffer-local_
|
|
dependencies.
|
|
A dependency with non-framebuffer-space pipeline stages is neither
|
|
framebuffer-global nor framebuffer-local.
|
|
|
|
A _framebuffer region_ is a set of sample (x, y, layer, sample) coordinates
|
|
that is a subset of the entire framebuffer.
|
|
|
|
A single framebuffer-local dependency guarantees that only for a single
|
|
framebuffer region, the first set of operations and availability operations
|
|
happen-before visibility operations and the second set of operations.
|
|
No ordering guarantees are made between framebuffer regions for a
|
|
framebuffer-local dependency.
|
|
|
|
A framebuffer-global dependency guarantees that the first set of operations
|
|
for all framebuffer regions happens-before the second set of operations for
|
|
any framebuffer region.
|
|
|
|
.Note
|
|
[NOTE]
|
|
====
|
|
Since fragment invocations are not specified to run in any particular
|
|
groupings, the size of a framebuffer region is implementation-dependent, not
|
|
known to the application, and must: be assumed to be no larger than a single
|
|
sample.
|
|
====
|
|
|
|
If a synchronization command includes a pname:dependencyFlags parameter, and
|
|
specifies the ename:VK_DEPENDENCY_BY_REGION_BIT flag, then it defines
|
|
framebuffer-local dependencies for the framebuffer-space pipeline stages in
|
|
that synchronization command, for all framebuffer regions.
|
|
If no pname:dependencyFlags parameter is included, or the
|
|
ename:VK_DEPENDENCY_BY_REGION_BIT flag is not specified, then a
|
|
framebuffer-global dependency is specified for those stages.
|
|
The ename:VK_DEPENDENCY_BY_REGION_BIT flag does not affect the dependencies
|
|
between non-framebuffer-space pipeline stages, nor does it affect the
|
|
dependencies between framebuffer-space and non-framebuffer-space pipeline
|
|
stages.
|
|
|
|
.Note
|
|
[NOTE]
|
|
====
|
|
Framebuffer-local dependencies are more optimal for most architectures;
|
|
particularly tile-based architectures - which can keep framebuffer-regions
|
|
entirely in on-chip registers and thus avoid external bandwidth across such
|
|
a dependency.
|
|
Including a framebuffer-global dependency in your rendering will usually
|
|
force all implementations to flush data to memory, or to a higher level
|
|
cache, breaking any potential locality optimizations.
|
|
====
|
|
|
|
|
|
[[synchronization-implicit]]
|
|
== Implicit Synchronization Guarantees
|
|
|
|
A small number of implicit ordering guarantees are provided by Vulkan,
|
|
ensuring that the order in which commands are submitted is meaningful, and
|
|
avoiding unnecessary complexity in common operations.
|
|
|
|
[[synchronization-submission-order]]
|
|
_Submission order_ is a fundamental ordering in Vulkan, giving meaning to
|
|
the order in which <<fundamentals-queueoperation-command-types, action and
|
|
synchronization commands>> are recorded and submitted to a single queue.
|
|
Explicit and implicit ordering guarantees between commands in Vulkan all
|
|
work on the premise that this ordering is meaningful.
|
|
|
|
Submission order for any given set of commands is based on the order in
|
|
which they were recorded to command buffers and then submitted.
|
|
This order is determined as follows:
|
|
|
|
. The initial order is determined by the order in which
|
|
flink:vkQueueSubmit commands are executed on the host, for a single
|
|
queue, from first to last.
|
|
. The order in which slink:VkSubmitInfo structures are specified in the
|
|
pname:pSubmits parameter of flink:vkQueueSubmit, from lowest index to
|
|
highest.
|
|
. The order in which command buffers are specified in the
|
|
pname:pCommandBuffers member of slink:VkSubmitInfo, from lowest index to
|
|
highest.
|
|
. The order in which commands were recorded to a command buffer on the
|
|
host, from first to last:
|
|
** For commands recorded outside a render pass, this includes all other
|
|
commands recorded outside a renderpass, including
|
|
flink:vkCmdBeginRenderPass and flink:vkCmdEndRenderPass commands; it
|
|
does not directly include commands inside a render pass.
|
|
** For commands recorded inside a render pass, this includes all other
|
|
commands recorded inside the same subpass, including the
|
|
flink:vkCmdBeginRenderPass and flink:vkCmdEndRenderPass commands that
|
|
delimit the same renderpass instance; it does not include commands
|
|
recorded to other subpasses.
|
|
|
|
<<fundamentals-queueoperation-command-types, Action and synchronization
|
|
commands>> recorded to a command buffer execute the
|
|
ename:VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT pipeline stage in
|
|
<<synchronization-submission-order, submission order>> - forming an implicit
|
|
execution dependency between this stage in each command.
|
|
|
|
<<fundamentals-queueoperation-command-types, State commands>> do not execute
|
|
any operations on the device, instead they set the state of the command
|
|
buffer when they execute on the host, in the order that they are recorded.
|
|
<<fundamentals-queueoperation-command-types, Action commands>> consume the
|
|
current state of the command buffer when they are recorded, and will execute
|
|
state changes on the device as required to match the recorded state.
|
|
|
|
<<queries-order, Query commands>>, <<drawing-primitive-order, the order of
|
|
primitives passing through the graphics pipeline>> and
|
|
<<synchronization-image-barrier-layout-transition-order, image layout
|
|
transitions as part of an image memory barrier>> provide additional
|
|
guarantees based on submission order.
|
|
|
|
Execution of <<synchronization-pipeline-stages-order, pipeline stages>>
|
|
within a given command also has a loose ordering, dependent only on a single
|
|
command.
|
|
|
|
|
|
[[synchronization-fences]]
|
|
== Fences
|
|
|
|
// refBegin VkFence Opaque handle to a fence object
|
|
|
|
Fences are a synchronization primitive that can: be used to insert a
|
|
dependency from a queue to the host.
|
|
Fences have two states - signaled and unsignaled.
|
|
A fence can: be signaled as part of the execution of a
|
|
<<devsandqueues-submission, queue submission>> command.
|
|
Fences can: be unsignaled on the host with flink:vkResetFences.
|
|
Fences can: be waited on by the host with the flink:vkWaitForFences command,
|
|
and the current state can: be queried with flink:vkGetFenceStatus.
|
|
|
|
Fences are represented by sname:VkFence handles:
|
|
|
|
include::../api/handles/VkFence.txt[]
|
|
|
|
// refEnd VkFence
|
|
|
|
// refBegin vkCreateFence Create a new fence object
|
|
|
|
To create a fence, call:
|
|
|
|
include::../api/protos/vkCreateFence.txt[]
|
|
|
|
* pname:device is the logical device that creates the fence.
|
|
* pname:pCreateInfo is a pointer to an instance of the
|
|
sname:VkFenceCreateInfo structure which contains information about how
|
|
the fence is to be created.
|
|
* pname:pAllocator controls host memory allocation as described in the
|
|
<<memory-allocation, Memory Allocation>> chapter.
|
|
* pname:pFence points to a handle in which the resulting fence object is
|
|
returned.
|
|
|
|
include::../validity/protos/vkCreateFence.txt[]
|
|
|
|
// refBegin VkFenceCreateInfo Structure specifying parameters of a newly created fence
|
|
|
|
The sname:VkFenceCreateInfo structure is defined as:
|
|
|
|
include::../api/structs/VkFenceCreateInfo.txt[]
|
|
|
|
* pname:sType is the type of this structure.
|
|
* pname:pNext is `NULL` or a pointer to an extension-specific structure.
|
|
* pname:flags defines the initial state and behavior of the fence.
|
|
Bits which can: be set include:
|
|
+
|
|
--
|
|
// refBegin VkFenceCreateFlagBits Bitmask specifying initial state and behavior of a fence
|
|
include::../api/enums/VkFenceCreateFlagBits.txt[]
|
|
--
|
|
+
|
|
If pname:flags contains ename:VK_FENCE_CREATE_SIGNALED_BIT then the fence
|
|
object is created in the signaled state; otherwise it is created in the
|
|
unsignaled state.
|
|
|
|
include::../validity/structs/VkFenceCreateInfo.txt[]
|
|
|
|
// refBegin vkDestroyFence Destroy a fence object
|
|
|
|
To destroy a fence, call:
|
|
|
|
include::../api/protos/vkDestroyFence.txt[]
|
|
|
|
* pname:device is the logical device that destroys the fence.
|
|
* pname:fence is the handle of the fence to destroy.
|
|
* pname:pAllocator controls host memory allocation as described in the
|
|
<<memory-allocation, Memory Allocation>> chapter.
|
|
|
|
.Valid Usage
|
|
****
|
|
* All <<devsandqueues-submission, queue submission>> commands that refer
|
|
to pname:fence must: have completed execution
|
|
* If sname:VkAllocationCallbacks were provided when pname:fence was
|
|
created, a compatible set of callbacks must: be provided here
|
|
* If no sname:VkAllocationCallbacks were provided when pname:fence was
|
|
created, pname:pAllocator must: be `NULL`
|
|
****
|
|
|
|
include::../validity/protos/vkDestroyFence.txt[]
|
|
|
|
// refBegin vkGetFenceStatus Return the status of a fence
|
|
|
|
To query the status of a fence from the host, call:
|
|
|
|
include::../api/protos/vkGetFenceStatus.txt[]
|
|
|
|
* pname:device is the logical device that owns the fence.
|
|
* pname:fence is the handle of the fence to query.
|
|
|
|
Upon success, fname:vkGetFenceStatus returns the status of the fence object,
|
|
with the following return codes:
|
|
|
|
.Fence Object Status Codes
|
|
[width="80%",options="header"]
|
|
|====
|
|
| Status | Meaning
|
|
| ename:VK_SUCCESS | The fence specified by pname:fence is signaled.
|
|
| ename:VK_NOT_READY | The fence specified by pname:fence is unsignaled.
|
|
|====
|
|
|
|
If a <<devsandqueues-submission, queue submission>> command is pending
|
|
execution, then the value returned by this command may: immediately be out
|
|
of date.
|
|
|
|
include::../validity/protos/vkGetFenceStatus.txt[]
|
|
|
|
[[synchronization-fences-unsignaling]]
|
|
// refBegin vkResetFences Resets one or more fence objects
|
|
|
|
To set the state of fences to unsignaled from the host, call:
|
|
|
|
include::../api/protos/vkResetFences.txt[]
|
|
|
|
* pname:device is the logical device that owns the fences.
|
|
* pname:fenceCount is the number of fences to reset.
|
|
* pname:pFences is a pointer to an array of fence handles to reset.
|
|
|
|
When flink:vkResetFences is executed on the host, it defines a _fence
|
|
unsignal operation_ for each fence, which resets the fence to the unsignaled
|
|
state.
|
|
|
|
If any member of pname:pFences is already in the unsignaled state when
|
|
flink:vkResetFences is executed, then flink:vkResetFences has no effect on
|
|
that fence.
|
|
|
|
.Valid Usage
|
|
****
|
|
* Any given element of pname:pFences must: not currently be associated
|
|
with any queue command that has not yet completed execution on that
|
|
queue
|
|
****
|
|
|
|
include::../validity/protos/vkResetFences.txt[]
|
|
|
|
[[synchronization-fences-signaling]]
|
|
When a fence is submitted to a queue as part of a
|
|
<<devsandqueues-submission, queue submission>> command, it defines a memory
|
|
dependency on the batches that were submitted as part of that command, and
|
|
defines a _fence signal operation_ which sets the fence to the signaled
|
|
state.
|
|
|
|
The first <<synchronization-dependencies-scopes, synchronization scope>>
|
|
includes every batch submitted in the same <<devsandqueues-submission, queue
|
|
submission>> command.
|
|
Fence signal operations that are defined by flink:vkQueueSubmit additionally
|
|
include in the first synchronization scope all previous queue submissions to
|
|
the same queue via flink:vkQueueSubmit.
|
|
|
|
The second <<synchronization-dependencies-scopes, synchronization scope>>
|
|
only includes the fence signal operation.
|
|
|
|
The first <<synchronization-dependencies-access-scopes, access scope>>
|
|
includes all memory access performed by the device.
|
|
|
|
The second <<synchronization-dependencies-access-scopes, access scope>> is
|
|
empty.
|
|
|
|
// refBegin vkWaitForFences Wait for one or more fences to become signaled
|
|
|
|
To wait for one or more fences to enter the signaled state on the host,
|
|
call:
|
|
|
|
include::../api/protos/vkWaitForFences.txt[]
|
|
|
|
* pname:device is the logical device that owns the fences.
|
|
* pname:fenceCount is the number of fences to wait on.
|
|
* pname:pFences is a pointer to an array of pname:fenceCount fence
|
|
handles.
|
|
* pname:waitAll is the condition that must: be satisfied to successfully
|
|
unblock the wait.
|
|
If pname:waitAll is ename:VK_TRUE, then the condition is that all fences
|
|
in pname:pFences are signaled.
|
|
Otherwise, the condition is that at least one fence in pname:pFences is
|
|
signaled.
|
|
* pname:timeout is the timeout period in units of nanoseconds.
|
|
pname:timeout is adjusted to the closest value allowed by the
|
|
implementation-dependent timeout accuracy, which may: be substantially
|
|
longer than one nanosecond, and may: be longer than the requested
|
|
period.
|
|
|
|
If the condition is satisfied when fname:vkWaitForFences is called, then
|
|
fname:vkWaitForFences returns immediately.
|
|
If the condition is not satisfied at the time fname:vkWaitForFences is
|
|
called, then fname:vkWaitForFences will block and wait up to pname:timeout
|
|
nanoseconds for the condition to become satisfied.
|
|
|
|
If pname:timeout is zero, then fname:vkWaitForFences does not wait, but
|
|
simply returns the current state of the fences.
|
|
ename:VK_TIMEOUT will be returned in this case if the condition is not
|
|
satisfied, even though no actual wait was performed.
|
|
|
|
If the specified timeout period expires before the condition is satisfied,
|
|
fname:vkWaitForFences returns ename:VK_TIMEOUT.
|
|
If the condition is satisfied before pname:timeout nanoseconds has expired,
|
|
fname:vkWaitForFences returns ename:VK_SUCCESS.
|
|
|
|
include::../validity/protos/vkWaitForFences.txt[]
|
|
|
|
[[synchronization-fences-waiting]]
|
|
An execution dependency is defined by waiting for a fence to become
|
|
signaled, either via flink:vkWaitForFences or by polling on
|
|
flink:vkGetFenceStatus.
|
|
|
|
The first <<synchronization-dependencies-scopes, synchronization scope>>
|
|
includes only the fence signal operation.
|
|
|
|
The second <<synchronization-dependencies-scopes, synchronization scope>>
|
|
includes the host operations of flink:vkWaitForFences or
|
|
flink:vkGetFenceStatus indicating that the fence has become signaled.
|
|
|
|
.Note
|
|
[NOTE]
|
|
====
|
|
Signaling a fence and waiting on the host does not guarantee that the
|
|
results of memory accesses will be visible to the host.
|
|
To provide that guarantee, the application must: insert a memory barrier
|
|
between the device writes and the end of the submission that will signal the
|
|
fence, with pname:dstAccessMask having the ename:VK_ACCESS_HOST_READ_BIT bit
|
|
set, with pname:dstStageMask having the ename:VK_PIPELINE_STAGE_HOST_BIT bit
|
|
set, and with the appropriate pname:srcStageMask and pname:srcAccessMask
|
|
members set to guarantee completion of the writes.
|
|
If the memory was allocated without the
|
|
ename:VK_MEMORY_PROPERTY_HOST_COHERENT_BIT set, then
|
|
fname:vkInvalidateMappedMemoryRanges must: be called after the fence is
|
|
signaled in order to ensure the writes are visible to the host, as described
|
|
in <<memory-device-hostaccess,Host Access to Device Memory Objects>>.
|
|
====
|
|
|
|
ifdef::VK_EXT_display_control[]
|
|
include::VK_EXT_display_control/fence_events.txt[]
|
|
endif::VK_EXT_display_control[]
|
|
|
|
[[synchronization-semaphores]]
|
|
== Semaphores
|
|
|
|
// refBegin VkSemaphore Opaque handle to a semaphore object
|
|
|
|
Semaphores are a synchronization primitive that can: be used to insert a
|
|
dependency between batches submitted to queues.
|
|
Semaphores have two states - signaled and unsignaled.
|
|
The state of a semaphore can: be signaled after execution of a batch of
|
|
commands is completed.
|
|
A batch can: wait for a semaphore to become signaled before it begins
|
|
execution, and the semaphore is also unsignaled before the batch begins
|
|
execution.
|
|
|
|
Semaphores are represented by sname:VkSemaphore handles:
|
|
|
|
include::../api/handles/VkSemaphore.txt[]
|
|
|
|
// refEnd VkSemaphore
|
|
|
|
// refBegin vkCreateSemaphore Create a new queue semaphore object
|
|
|
|
To create a semaphore, call:
|
|
|
|
include::../api/protos/vkCreateSemaphore.txt[]
|
|
|
|
* pname:device is the logical device that creates the semaphore.
|
|
* pname:pCreateInfo is a pointer to an instance of the
|
|
sname:VkSemaphoreCreateInfo structure which contains information about
|
|
how the semaphore is to be created.
|
|
* pname:pAllocator controls host memory allocation as described in the
|
|
<<memory-allocation, Memory Allocation>> chapter.
|
|
* pname:pSemaphore points to a handle in which the resulting semaphore
|
|
object is returned.
|
|
|
|
When created, the semaphore is in the unsignaled state.
|
|
|
|
include::../validity/protos/vkCreateSemaphore.txt[]
|
|
|
|
// refBegin VkSemaphoreCreateInfo Structure specifying parameters of a newly created semaphore
|
|
|
|
The sname:VkSemaphoreCreateInfo structure is defined as:
|
|
|
|
include::../api/structs/VkSemaphoreCreateInfo.txt[]
|
|
|
|
* pname:sType is the type of this structure.
|
|
* pname:pNext is `NULL` or a pointer to an extension-specific structure.
|
|
* pname:flags is reserved for future use.
|
|
|
|
include::../validity/structs/VkSemaphoreCreateInfo.txt[]
|
|
|
|
// refBegin vkDestroySemaphore Destroy a semaphore object
|
|
|
|
To destroy a semaphore, call:
|
|
|
|
include::../api/protos/vkDestroySemaphore.txt[]
|
|
|
|
* pname:device is the logical device that destroys the semaphore.
|
|
* pname:semaphore is the handle of the semaphore to destroy.
|
|
* pname:pAllocator controls host memory allocation as described in the
|
|
<<memory-allocation, Memory Allocation>> chapter.
|
|
|
|
.Valid Usage
|
|
****
|
|
* All submitted batches that refer to pname:semaphore must: have completed
|
|
execution
|
|
* If sname:VkAllocationCallbacks were provided when pname:semaphore was
|
|
created, a compatible set of callbacks must: be provided here
|
|
* If no sname:VkAllocationCallbacks were provided when pname:semaphore was
|
|
created, pname:pAllocator must: be `NULL`
|
|
****
|
|
|
|
include::../validity/protos/vkDestroySemaphore.txt[]
|
|
|
|
|
|
[[synchronization-semaphores-signaling]]
|
|
=== Semaphore Signaling
|
|
|
|
When a batch is submitted to a queue via a <<devsandqueues-submission, queue
|
|
submission>>, and it includes semaphores to be signaled, it defines a memory
|
|
dependency on the batch, and defines _semaphore signal operations_ which set
|
|
the semaphores to the signaled state.
|
|
|
|
The first <<synchronization-dependencies-scopes, synchronization scope>>
|
|
includes every command submitted in the same batch.
|
|
Semaphore signal operations that are defined by flink:vkQueueSubmit
|
|
additionally include all batches previously submitted to the same queue via
|
|
flink:vkQueueSubmit, including batches that are submitted in the same
|
|
<<devsandqueues-submission, queue submission>> command, but at a lower index
|
|
within the array of batches.
|
|
|
|
The second <<synchronization-dependencies-scopes, synchronization scope>>
|
|
includes only the semaphore signal operation.
|
|
|
|
The first <<synchronization-dependencies-access-scopes, access scope>>
|
|
includes all memory access performed by the device.
|
|
|
|
The second <<synchronization-dependencies-access-scopes, access scope>> is
|
|
empty.
|
|
|
|
|
|
[[synchronization-semaphores-waiting]]
|
|
=== Semaphore Waiting & Unsignaling
|
|
|
|
When a batch is submitted to a queue via a <<devsandqueues-submission, queue
|
|
submission>>, and it includes semaphores to be waited on, it defines a
|
|
memory dependency between prior semaphore signal operations and the batch,
|
|
and defines _semaphore unsignal operations_ which set the semaphores to the
|
|
unsignaled state.
|
|
|
|
The first synchronization scope includes all semaphore signal operations
|
|
that operate on semaphores waited on in the same batch, and that
|
|
happen-before the wait completes.
|
|
|
|
The second <<synchronization-dependencies-scopes, synchronization scope>>
|
|
includes every command submitted in the same batch.
|
|
In the case of flink:vkQueueSubmit, the second synchronization scope is
|
|
limited to operations on the pipeline stages determined by the
|
|
<<synchronization-pipeline-stages-masks, destination stage mask>> specified
|
|
by the corresponding element of pname:pWaitDstStageMask.
|
|
Also, in the case of flink:vkQueueSubmit, the second synchronization scope
|
|
additionally includes all batches subsequently submitted to the same queue
|
|
via flink:vkQueueSubmit, including batches that are submitted in the same
|
|
<<devsandqueues-submission, queue submission>> command, but at a higher
|
|
index within the array of batches.
|
|
|
|
The first <<synchronization-dependencies-access-scopes, access scope>> is
|
|
empty.
|
|
|
|
The second <<synchronization-dependencies-access-scopes, access scope>>
|
|
includes all memory access performed by the device.
|
|
|
|
The semaphore unsignal operation happens-after the first set of operations
|
|
in the execution dependency, and happens-before the second set of operations
|
|
in the execution dependency.
|
|
|
|
.Note
|
|
[NOTE]
|
|
====
|
|
Unlike fences or events, the act of waiting for a semaphore also unsignals
|
|
that semaphore.
|
|
If two operations are separately specified to wait for the same semaphore,
|
|
and there are no other execution dependencies between those operations,
|
|
behaviour is undefined.
|
|
An execution dependency must: be present that guarantees that the semaphore
|
|
unsignal operation for the first of those waits, happens-before the
|
|
semaphore is signalled again, and before the second unsignal operation.
|
|
Semaphore waits and signals should thus occur in discrete 1:1 pairs.
|
|
====
|
|
|
|
ifdef::VK_KHR_swapchain[]
|
|
.Note
|
|
[NOTE]
|
|
====
|
|
A common scenario for using pname:pWaitDstStageMask with values other than
|
|
ename:VK_PIPELINE_STAGE_ALL_COMMANDS_BIT is when synchronizing a window
|
|
system presentation operation against subsequent command buffers which
|
|
render the next frame.
|
|
In this case, a presentation image must: not be overwritten until the
|
|
presentation operation completes, but other pipeline stages can: execute
|
|
without waiting.
|
|
A mask of ename:VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT prevents
|
|
subsequent color attachment writes from executing until the semaphore
|
|
signals.
|
|
Some implementations may: be able to execute transfer operations and/or
|
|
vertex processing work before the semaphore is signaled.
|
|
|
|
If an image layout transition needs to be performed on a presentable image
|
|
before it is used in a framebuffer, that can: be performed as the first
|
|
operation submitted to the queue after acquiring the image, and should: not
|
|
prevent other work from overlapping with the presentation operation.
|
|
For example, a sname:VkImageMemoryBarrier could use:
|
|
|
|
* pname:srcStageMask = ename:VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT
|
|
* pname:srcAccessMask = 0
|
|
* pname:dstStageMask = ename:VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT
|
|
* pname:dstAccessMask = ename:VK_ACCESS_COLOR_ATTACHMENT_READ_BIT |
|
|
ename:VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT.
|
|
* pname:oldLayout = etext:VK_IMAGE_LAYOUT_PRESENT_SRC_KHR
|
|
* pname:newLayout = ename:VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL
|
|
|
|
Alternatively, pname:oldLayout can: be ename:VK_IMAGE_LAYOUT_UNDEFINED, if
|
|
the image's contents need not be preserved.
|
|
|
|
This barrier accomplishes a dependency chain between previous presentation
|
|
operations and subsequent color attachment output operations, with the
|
|
layout transition performed in between, and does not introduce a dependency
|
|
between previous work and any vertex processing stages.
|
|
More precisely, the semaphore signals after the presentation operation
|
|
completes, the semaphore wait stalls the
|
|
ename:VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT stage, and there is a
|
|
dependency from that same stage to itself with the layout transition
|
|
performed in between.
|
|
====
|
|
endif::VK_KHR_swapchain[]
|
|
|
|
|
|
[[synchronization-events]]
|
|
== Events
|
|
|
|
// refBegin VkEvent Opaque handle to a event object
|
|
|
|
Events are a synchronization primitive that can: be used to insert a
|
|
fine-grained dependency between commands submitted to the same queue, or
|
|
between the host and a queue.
|
|
Events have two states - signaled and unsignaled.
|
|
An application can: signal an event, or unsignal it, on either the host or
|
|
the device.
|
|
A device can: wait for an event to become signaled before executing further
|
|
operations.
|
|
No command exists to wait for an event to become signaled on the host, but
|
|
the current state of an event can: be queried.
|
|
|
|
Events are represented by sname:VkEvent handles:
|
|
|
|
include::../api/handles/VkEvent.txt[]
|
|
|
|
// refEnd VkEvent
|
|
|
|
// refBegin vkCreateEvent Create a new event object
|
|
|
|
To create an event, call:
|
|
|
|
include::../api/protos/vkCreateEvent.txt[]
|
|
|
|
* pname:device is the logical device that creates the event.
|
|
* pname:pCreateInfo is a pointer to an instance of the
|
|
sname:VkEventCreateInfo structure which contains information about how
|
|
the event is to be created.
|
|
* pname:pAllocator controls host memory allocation as described in the
|
|
<<memory-allocation, Memory Allocation>> chapter.
|
|
* pname:pEvent points to a handle in which the resulting event object is
|
|
returned.
|
|
|
|
When created, the event object is in the unsignaled state.
|
|
|
|
include::../validity/protos/vkCreateEvent.txt[]
|
|
|
|
// refBegin VkEventCreateInfo Structure specifying parameters of a newly created event
|
|
|
|
The sname:VkEventCreateInfo structure is defined as:
|
|
|
|
include::../api/structs/VkEventCreateInfo.txt[]
|
|
|
|
* pname:sType is the type of this structure.
|
|
* pname:pNext is `NULL` or a pointer to an extension-specific structure.
|
|
* pname:flags is reserved for future use.
|
|
|
|
include::../validity/structs/VkEventCreateInfo.txt[]
|
|
|
|
// refBegin vkDestroyEvent Destroy an event object
|
|
|
|
To destroy an event, call:
|
|
|
|
include::../api/protos/vkDestroyEvent.txt[]
|
|
|
|
* pname:device is the logical device that destroys the event.
|
|
* pname:event is the handle of the event to destroy.
|
|
* pname:pAllocator controls host memory allocation as described in the
|
|
<<memory-allocation, Memory Allocation>> chapter.
|
|
|
|
.Valid Usage
|
|
****
|
|
* All submitted commands that refer to pname:event must: have completed
|
|
execution
|
|
* If sname:VkAllocationCallbacks were provided when pname:event was
|
|
created, a compatible set of callbacks must: be provided here
|
|
* If no sname:VkAllocationCallbacks were provided when pname:event was
|
|
created, pname:pAllocator must: be `NULL`
|
|
****
|
|
|
|
include::../validity/protos/vkDestroyEvent.txt[]
|
|
|
|
// refBegin vkGetEventStatus Retrieve the status of an event object
|
|
|
|
To query the state of an event from the host, call:
|
|
|
|
include::../api/protos/vkGetEventStatus.txt[]
|
|
|
|
* pname:device is the logical device that owns the event.
|
|
* pname:event is the handle of the event to query.
|
|
|
|
Upon success, fname:vkGetEventStatus returns the state of the event object
|
|
with the following return codes:
|
|
|
|
.Event Object Status Codes
|
|
[width="80%",options="header"]
|
|
|====
|
|
| Status | Meaning
|
|
| ename:VK_EVENT_SET | The event specified by pname:event is signaled.
|
|
| ename:VK_EVENT_RESET | The event specified by pname:event is unsignaled.
|
|
|====
|
|
|
|
If a fname:vkCmdSetEvent or fname:vkCmdResetEvent command is pending
|
|
execution, then the value returned by this command may: immediately be out
|
|
of date.
|
|
|
|
The state of an event can: be updated by the host.
|
|
The state of the event is immediately changed, and subsequent calls to
|
|
fname:vkGetEventStatus will return the new state.
|
|
If an event is already in the requested state, then updating it to the same
|
|
state has no effect.
|
|
|
|
include::../validity/protos/vkGetEventStatus.txt[]
|
|
|
|
[[synchronization-events-signaling-host]]
|
|
// refBegin vkSetEvent Set an event to signaled state
|
|
|
|
To set the state of an event to signaled from the host, call:
|
|
|
|
include::../api/protos/vkSetEvent.txt[]
|
|
|
|
* pname:device is the logical device that owns the event.
|
|
* pname:event is the event to set.
|
|
|
|
When flink:vkSetEvent is executed on the host, it defines an _event signal
|
|
operation_ which sets the event to the signaled state.
|
|
|
|
If pname:event is already in the signaled state when flink:vkSetEvent is
|
|
executed, then flink:vkSetEvent has no effect, and no event signal operation
|
|
occurs.
|
|
|
|
include::../validity/protos/vkSetEvent.txt[]
|
|
|
|
[[synchronization-events-unsignaling-host]]
|
|
// refBegin vkResetEvent Reset an event to non-signaled state
|
|
|
|
To set the state of an event to unsignaled from the host, call:
|
|
|
|
include::../api/protos/vkResetEvent.txt[]
|
|
|
|
* pname:device is the logical device that owns the event.
|
|
* pname:event is the event to reset.
|
|
|
|
When flink:vkResetEvent is executed on the host, it defines an _event
|
|
unsignal operation_ which resets the event to the unsignaled state.
|
|
|
|
If pname:event is already in the unsignaled state when flink:vkResetEvent is
|
|
executed, then flink:vkResetEvent has no effect, and no event unsignal
|
|
operation occurs.
|
|
|
|
.Valid Usage
|
|
****
|
|
* pname:event must: not be waited on by a fname:vkCmdWaitEvents command
|
|
that is currently executing
|
|
****
|
|
|
|
include::../validity/protos/vkResetEvent.txt[]
|
|
|
|
|
|
The state of an event can: also be updated on the device by commands
|
|
inserted in command buffers.
|
|
|
|
[[synchronization-events-signaling-device]]
|
|
// refBegin vkCmdSetEvent Set an event object to signaled state
|
|
|
|
To set the state of an event to signaled from a device, call:
|
|
|
|
include::../api/protos/vkCmdSetEvent.txt[]
|
|
|
|
* pname:commandBuffer is the command buffer into which the command is
|
|
recorded.
|
|
* pname:event is the event that will be signaled.
|
|
* pname:stageMask specifies the <<synchronization-pipeline-stages,source
|
|
stage mask>> used to determine when the pname:event is signaled.
|
|
|
|
When flink:vkCmdSetEvent is submitted to a queue, it defines an execution
|
|
dependency on commands that were submitted before it, and defines an event
|
|
signal operation which sets the event to the signaled state.
|
|
|
|
The first <<synchronization-dependencies-scopes, synchronization scope>>
|
|
includes every command previously submitted to the same queue, including
|
|
those in the same command buffer and batch.
|
|
The synchronization scope is limited to operations on the pipeline stages
|
|
determined by the <<synchronization-pipeline-stages-masks, source stage
|
|
mask>> specified by pname:stageMask.
|
|
|
|
The second <<synchronization-dependencies-scopes, synchronization scope>>
|
|
includes only the event signal operation.
|
|
|
|
If pname:event is already in the signaled state when flink:vkCmdSetEvent is
|
|
executed on the device, then flink:vkCmdSetEvent has no effect, no event
|
|
signal operation occurs, and no execution dependency is generated.
|
|
|
|
.Valid Usage
|
|
****
|
|
* pname:stageMask must: not include ename:VK_PIPELINE_STAGE_HOST_BIT
|
|
* If the <<features-features-geometryShader,geometry shaders>> feature is
|
|
not enabled, pname:stageMask must: not contain
|
|
ename:VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT
|
|
* If the <<features-features-tessellationShader,tessellation shaders>>
|
|
feature is not enabled, pname:stageMask must: not contain
|
|
ename:VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT or
|
|
ename:VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT
|
|
****
|
|
|
|
include::../validity/protos/vkCmdSetEvent.txt[]
|
|
|
|
[[synchronization-events-unsignaling-device]]
|
|
// refBegin vkCmdResetEvent Reset an event object to non-signaled state
|
|
|
|
To set the state of an event to unsignaled from a device, call:
|
|
|
|
include::../api/protos/vkCmdResetEvent.txt[]
|
|
|
|
* pname:commandBuffer is the command buffer into which the command is
|
|
recorded.
|
|
* pname:event is the event that will be unsignaled.
|
|
* pname:stageMask specifies the <<synchronization-pipeline-stages,source
|
|
stage mask>> used to determine when the pname:event is unsignaled.
|
|
|
|
When flink:vkCmdResetEvent is submitted to a queue, it defines an execution
|
|
dependency on commands that were submitted before it, and defines an event
|
|
unsignal operation which resets the event to the unsignaled state.
|
|
|
|
The first <<synchronization-dependencies-scopes, synchronization scope>>
|
|
includes every command previously submitted to the same queue, including
|
|
those in the same command buffer and batch.
|
|
The synchronization scope is limited to operations on the pipeline stages
|
|
determined by the <<synchronization-pipeline-stages-masks, source stage
|
|
mask>> specified by pname:stageMask.
|
|
|
|
The second <<synchronization-dependencies-scopes, synchronization scope>>
|
|
includes only the event unsignal operation.
|
|
|
|
If pname:event is already in the unsignaled state when flink:vkCmdResetEvent
|
|
is executed on the device, then flink:vkCmdResetEvent has no effect, no
|
|
event unsignal operation occurs, and no execution dependency is generated.
|
|
|
|
.Valid Usage
|
|
****
|
|
* pname:stageMask must: not include ename:VK_PIPELINE_STAGE_HOST_BIT
|
|
* If the <<features-features-geometryShader,geometry shaders>> feature is
|
|
not enabled, pname:stageMask must: not contain
|
|
ename:VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT
|
|
* If the <<features-features-tessellationShader,tessellation shaders>>
|
|
feature is not enabled, pname:stageMask must: not contain
|
|
ename:VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT or
|
|
ename:VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT
|
|
* When this command executes, pname:event must: not be waited on by a
|
|
fname:vkCmdWaitEvents command that is currently executing
|
|
****
|
|
|
|
include::../validity/protos/vkCmdResetEvent.txt[]
|
|
|
|
// refBegin vkCmdWaitEvents Wait for one or more events and insert a set of memory
|
|
|
|
To wait for one or more events to enter the signaled state on a device,
|
|
call:
|
|
|
|
[[synchronization-events-waiting-device]]
|
|
include::../api/protos/vkCmdWaitEvents.txt[]
|
|
|
|
* pname:commandBuffer is the command buffer into which the command is
|
|
recorded.
|
|
* pname:eventCount is the length of the pname:pEvents array.
|
|
* pname:pEvents is an array of event object handles to wait on.
|
|
* pname:srcStageMask is the <<synchronization-pipeline-stages, source
|
|
stage mask>>
|
|
* pname:dstStageMask is the <<synchronization-pipeline-stages, destination
|
|
stage mask>>.
|
|
* pname:memoryBarrierCount is the length of the pname:pMemoryBarriers
|
|
array.
|
|
* pname:pMemoryBarriers is a pointer to an array of slink:VkMemoryBarrier
|
|
structures.
|
|
* pname:bufferMemoryBarrierCount is the length of the
|
|
pname:pBufferMemoryBarriers array.
|
|
* pname:pBufferMemoryBarriers is a pointer to an array of
|
|
slink:VkBufferMemoryBarrier structures.
|
|
* pname:imageMemoryBarrierCount is the length of the
|
|
pname:pImageMemoryBarriers array.
|
|
* pname:pImageMemoryBarriers is a pointer to an array of
|
|
slink:VkImageMemoryBarrier structures.
|
|
|
|
When fname:vkCmdWaitEvents is submitted to a queue, it defines a memory
|
|
dependency between prior event signal operations, and subsequent commands.
|
|
|
|
The first synchronization scope only includes event signal operations that
|
|
operate on members of pname:pEvents, and the operations that happened-before
|
|
the event signal operations.
|
|
Event signal operations performed by flink:vkCmdSetEvent that were
|
|
previously submitted to the same queue are included in the first
|
|
synchronization scope, if the <<synchronization-pipeline-stages-order,
|
|
logically latest>> pipeline stage in their pname:stageMask parameter is
|
|
<<synchronization-pipeline-stages-order, logically earlier>> than or equal
|
|
to the <<synchronization-pipeline-stages-order, logically latest>> pipeline
|
|
stage in pname:srcStageMask.
|
|
Event signal operations performed by flink:vkSetEvent are only included in
|
|
the first synchronization scope if ename:VK_PIPELINE_STAGE_HOST_BIT is
|
|
included in pname:srcStageMask.
|
|
|
|
The second <<synchronization-dependencies-scopes, synchronization scope>>
|
|
includes commands subsequently submitted to the same queue, including those
|
|
in the same command buffer and batch.
|
|
The second synchronization scope is limited to operations on the pipeline
|
|
stages determined by the <<synchronization-pipeline-stages-masks,
|
|
destination stage mask>> specified by pname:dstStageMask.
|
|
|
|
The first <<synchronization-dependencies-access-scopes, access scope>> is
|
|
limited to access in the pipeline stages determined by the
|
|
<<synchronization-pipeline-stages-masks, source stage mask>> specified by
|
|
pname:srcStageMask.
|
|
Within that, the first access scope only includes the first access scopes
|
|
defined by elements of the pname:pMemoryBarriers,
|
|
pname:pBufferMemoryBarriers and pname:pImageMemoryBarriers arrays, which
|
|
each define a set of <<synchronization-memory-barriers, memory barriers>>.
|
|
If no memory barriers are specified, then the first access scope includes no
|
|
accesses.
|
|
|
|
The second <<synchronization-dependencies-access-scopes, access scope>> is
|
|
limited to access in the pipeline stages determined by the
|
|
<<synchronization-pipeline-stages-masks, destination stage mask>> specified
|
|
by pname:dstStageMask.
|
|
Within that, the second access scope only includes the second access scopes
|
|
defined by elements of the pname:pMemoryBarriers,
|
|
pname:pBufferMemoryBarriers and pname:pImageMemoryBarriers arrays, which
|
|
each define a set of <<synchronization-memory-barriers, memory barriers>>.
|
|
If no memory barriers are specified, then the second access scope includes
|
|
no accesses.
|
|
|
|
[NOTE]
|
|
.Note
|
|
====
|
|
flink:vkCmdWaitEvents is used with flink:vkCmdSetEvent to define a memory
|
|
dependency between two sets of action commands, roughly in the same way as
|
|
pipeline barriers, but split into two commands such that work between the
|
|
two may: execute unhindered.
|
|
====
|
|
|
|
[NOTE]
|
|
.Note
|
|
====
|
|
Applications should: be careful to avoid race conditions when using events.
|
|
There is no direct ordering guarantee between a flink:vkCmdResetEvent
|
|
command and a flink:vkCmdWaitEvents command submitted after it, so some
|
|
other execution dependency must: be included between these commands (e.g. a
|
|
semaphore).
|
|
====
|
|
|
|
.Valid Usage
|
|
****
|
|
* pname:srcStageMask must: be the bitwise OR of the pname:stageMask
|
|
parameter used in previous calls to fname:vkCmdSetEvent with any of the
|
|
members of pname:pEvents and ename:VK_PIPELINE_STAGE_HOST_BIT if any of
|
|
the members of pname:pEvents was set using fname:vkSetEvent
|
|
* If the <<features-features-geometryShader,geometry shaders>> feature is
|
|
not enabled, pname:srcStageMask must: not contain
|
|
ename:VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT
|
|
* If the <<features-features-geometryShader,geometry shaders>> feature is
|
|
not enabled, pname:dstStageMask must: not contain
|
|
ename:VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT
|
|
* If the <<features-features-tessellationShader,tessellation shaders>>
|
|
feature is not enabled, pname:srcStageMask must: not contain
|
|
ename:VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT or
|
|
ename:VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT
|
|
* If the <<features-features-tessellationShader,tessellation shaders>>
|
|
feature is not enabled, pname:dstStageMask must: not contain
|
|
ename:VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT or
|
|
ename:VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT
|
|
* If pname:pEvents includes one or more events that will be signaled by
|
|
fname:vkSetEvent after pname:commandBuffer has been submitted to a
|
|
queue, then fname:vkCmdWaitEvents must: not be called inside a render
|
|
pass instance
|
|
* Any pipeline stage included in pname:srcStageMask or pname:dstStageMask
|
|
must: be supported by the capabilities of the queue family specified by
|
|
the pname:queueFamilyIndex member of the slink:VkCommandPoolCreateInfo
|
|
structure that was used to create the sname:VkCommandPool that
|
|
pname:commandBuffer was allocated from, as specified in the
|
|
<<synchronization-pipeline-stages-supported, table of supported pipeline
|
|
stages>>.
|
|
* Any given element of pname:pMemoryBarriers, pname:pBufferMemoryBarriers
|
|
or pname:pImageMemoryBarriers must: not have any access flag included in
|
|
its pname:srcAccessMask member if that bit is not supported by any of
|
|
the pipeline stages in pname:srcStageMask, as specified in the
|
|
<<synchronization-access-types-supported, table of supported access
|
|
types>>.
|
|
* Any given element of pname:pMemoryBarriers, pname:pBufferMemoryBarriers
|
|
or pname:pImageMemoryBarriers must: not have any access flag included in
|
|
its pname:dstAccessMask member if that bit is not supported by any of
|
|
the pipeline stages in pname:dstStageMask, as specified in the
|
|
<<synchronization-access-types-supported, table of supported access
|
|
types>>.
|
|
****
|
|
|
|
include::../validity/protos/vkCmdWaitEvents.txt[]
|
|
|
|
|
|
[[synchronization-pipeline-barriers]]
|
|
== Pipeline Barriers
|
|
|
|
flink:vkCmdPipelineBarrier is a synchronization command that inserts a
|
|
dependency between commands submitted to the same queue, or between commands
|
|
in the same subpass.
|
|
|
|
// refBegin vkCmdPipelineBarrier Insert a memory dependency
|
|
|
|
To record a pipeline barrier, call:
|
|
|
|
include::../api/protos/vkCmdPipelineBarrier.txt[]
|
|
|
|
* pname:commandBuffer is the command buffer into which the command is
|
|
recorded.
|
|
* pname:srcStageMask defines a <<synchronization-pipeline-stages-masks,
|
|
source stage mask>>.
|
|
* pname:dstStageMask defines a <<synchronization-pipeline-stages-masks,
|
|
destination stage mask>>.
|
|
* pname:dependencyFlags is a bitmask of elink:VkDependencyFlagBits.
|
|
The bits that can: be included in pname:dependencyFlags are:
|
|
+
|
|
--
|
|
// refBegin VkDependencyFlagBits Bitmask specifying how execution and memory dependencies are formed
|
|
include::../api/enums/VkDependencyFlagBits.txt[]
|
|
--
|
|
** ename:VK_DEPENDENCY_BY_REGION_BIT signifies that dependencies will be
|
|
<<synchronization-framebuffer-regions, framebuffer-local>>.
|
|
|
|
* pname:memoryBarrierCount is the length of the pname:pMemoryBarriers
|
|
array.
|
|
* pname:pMemoryBarriers is a pointer to an array of slink:VkMemoryBarrier
|
|
structures.
|
|
* pname:bufferMemoryBarrierCount is the length of the
|
|
pname:pBufferMemoryBarriers array.
|
|
* pname:pBufferMemoryBarriers is a pointer to an array of
|
|
slink:VkBufferMemoryBarrier structures.
|
|
* pname:imageMemoryBarrierCount is the length of the
|
|
pname:pImageMemoryBarriers array.
|
|
* pname:pImageMemoryBarriers is a pointer to an array of
|
|
slink:VkImageMemoryBarrier structures.
|
|
|
|
When flink:vkCmdPipelineBarrier is submitted to a queue, it defines a memory
|
|
dependency between commands that were submitted before it, and those
|
|
submitted after it.
|
|
|
|
If flink:vkCmdPipelineBarrier was recorded outside a render pass instance,
|
|
the first <<synchronization-dependencies-scopes, synchronization scope>>
|
|
includes every command submitted to the same queue before it, including
|
|
those in the same command buffer and batch.
|
|
If flink:vkCmdPipelineBarrier was recorded inside a render pass instance,
|
|
the first synchronization scope includes only commands submitted before it
|
|
within the same subpass.
|
|
In either case, the first synchronization scope is limited to operations on
|
|
the pipeline stages determined by the
|
|
<<synchronization-pipeline-stages-masks, source stage mask>> specified by
|
|
pname:srcStageMask.
|
|
|
|
If flink:vkCmdPipelineBarrier was recorded outside a render pass instance,
|
|
the second <<synchronization-dependencies-scopes, synchronization scope>>
|
|
includes every command submitted to the same queue after it, including those
|
|
in the same command buffer and batch.
|
|
If flink:vkCmdPipelineBarrier was recorded inside a render pass instance,
|
|
the second synchronization scope includes only commands submitted after it
|
|
within the same subpass.
|
|
In either case, the second synchronization scope is limited to operations on
|
|
the pipeline stages determined by the
|
|
<<synchronization-pipeline-stages-masks, destination stage mask>> specified
|
|
by pname:dstStageMask.
|
|
|
|
The first <<synchronization-dependencies-access-scopes, access scope>> is
|
|
limited to access in the pipeline stages determined by the
|
|
<<synchronization-pipeline-stages-masks, source stage mask>> specified by
|
|
pname:srcStageMask.
|
|
Within that, the first access scope only includes the first access scopes
|
|
defined by elements of the pname:pMemoryBarriers,
|
|
pname:pBufferMemoryBarriers and pname:pImageMemoryBarriers arrays, which
|
|
each define a set of <<synchronization-memory-barriers, memory barriers>>.
|
|
If no memory barriers are specified, then the first access scope includes no
|
|
accesses.
|
|
|
|
The second <<synchronization-dependencies-access-scopes, access scope>> is
|
|
limited to access in the pipeline stages determined by the
|
|
<<synchronization-pipeline-stages-masks, destination stage mask>> specified
|
|
by pname:dstStageMask.
|
|
Within that, the second access scope only includes the second access scopes
|
|
defined by elements of the pname:pMemoryBarriers,
|
|
pname:pBufferMemoryBarriers and pname:pImageMemoryBarriers arrays, which
|
|
each define a set of <<synchronization-memory-barriers, memory barriers>>.
|
|
If no memory barriers are specified, then the second access scope includes
|
|
no accesses.
|
|
|
|
If pname:dependencyFlags includes ename:VK_DEPENDENCY_BY_REGION_BIT, then
|
|
any dependency between <<synchronization-framebuffer-regions,
|
|
framebuffer-space>> pipeline stages is
|
|
<<synchronization-framebuffer-regions, framebuffer-local>> - otherwise it is
|
|
<<synchronization-framebuffer-regions, framebuffer-global>>.
|
|
|
|
.Valid Usage
|
|
****
|
|
* If the <<features-features-geometryShader,geometry shaders>> feature is
|
|
not enabled, pname:srcStageMask must: not contain
|
|
ename:VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT
|
|
* If the <<features-features-geometryShader,geometry shaders>> feature is
|
|
not enabled, pname:dstStageMask must: not contain
|
|
ename:VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT
|
|
* If the <<features-features-tessellationShader,tessellation shaders>>
|
|
feature is not enabled, pname:srcStageMask must: not contain
|
|
ename:VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT or
|
|
ename:VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT
|
|
* If the <<features-features-tessellationShader,tessellation shaders>>
|
|
feature is not enabled, pname:dstStageMask must: not contain
|
|
ename:VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT or
|
|
ename:VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT
|
|
* If fname:vkCmdPipelineBarrier is called within a render pass instance,
|
|
the render pass must: have been created with a sname:VkSubpassDependency
|
|
instance in pname:pDependencies that expresses a dependency from the
|
|
current subpass to itself.
|
|
Additionally:
|
|
** pname:srcStageMask must: contain a subset of the bit values in the
|
|
pname:srcStageMask member of that instance of sname:VkSubpassDependency
|
|
** pname:dstStageMask must: contain a subset of the bit values in the
|
|
pname:dstStageMask member of that instance of sname:VkSubpassDependency
|
|
** The pname:srcAccessMask of any element of pname:pMemoryBarriers or
|
|
pname:pImageMemoryBarriers must: contain a subset of the bit values the
|
|
pname:srcAccessMask member of that instance of
|
|
sname:VkSubpassDependency
|
|
** The pname:dstAccessMask of any element of pname:pMemoryBarriers or
|
|
pname:pImageMemoryBarriers must: contain a subset of the bit values the
|
|
pname:dstAccessMask member of that instance of
|
|
sname:VkSubpassDependency
|
|
** pname:dependencyFlags must: be equal to the pname:dependencyFlags
|
|
member of that instance of sname:VkSubpassDependency
|
|
* If fname:vkCmdPipelineBarrier is called within a render pass instance,
|
|
pname:bufferMemoryBarrierCount must: be `0`
|
|
* If fname:vkCmdPipelineBarrier is called within a render pass instance,
|
|
the pname:image member of any element of pname:pImageMemoryBarriers
|
|
must: be equal to one of the elements of pname:pAttachments that the
|
|
current pname:framebuffer was created with, that is also referred to by
|
|
one of the elements of the pname:pColorAttachments,
|
|
pname:pResolveAttachments or pname:pDepthStencilAttachment members of
|
|
the sname:VkSubpassDescription instance that the current subpass was
|
|
created with
|
|
* If fname:vkCmdPipelineBarrier is called within a render pass instance,
|
|
the pname:oldLayout and pname:newLayout members of any element of
|
|
pname:pImageMemoryBarriers must: be equal to the pname:layout member of
|
|
an element of the pname:pColorAttachments, pname:pResolveAttachments or
|
|
pname:pDepthStencilAttachment members of the sname:VkSubpassDescription
|
|
instance that the current subpass was created with, that refers to the
|
|
same pname:image
|
|
* If fname:vkCmdPipelineBarrier is called within a render pass instance,
|
|
the pname:oldLayout and pname:newLayout members of an element of
|
|
pname:pImageMemoryBarriers must: be equal
|
|
* If fname:vkCmdPipelineBarrier is called within a render pass instance,
|
|
the pname:srcQueueFamilyIndex and pname:dstQueueFamilyIndex members of
|
|
any element of pname:pImageMemoryBarriers must: be
|
|
ename:VK_QUEUE_FAMILY_IGNORED
|
|
* Any pipeline stage included in pname:srcStageMask or pname:dstStageMask
|
|
must: be supported by the capabilities of the queue family specified by
|
|
the pname:queueFamilyIndex member of the slink:VkCommandPoolCreateInfo
|
|
structure that was used to create the sname:VkCommandPool that
|
|
pname:commandBuffer was allocated from, as specified in the
|
|
<<synchronization-pipeline-stages-supported, table of supported pipeline
|
|
stages>>.
|
|
* Any given element of pname:pMemoryBarriers, pname:pBufferMemoryBarriers
|
|
or pname:pImageMemoryBarriers must: not have any access flag included in
|
|
its pname:srcAccessMask member if that bit is not supported by any of
|
|
the pipeline stages in pname:srcStageMask, as specified in the
|
|
<<synchronization-access-types-supported, table of supported access
|
|
types>>.
|
|
* Any given element of pname:pMemoryBarriers, pname:pBufferMemoryBarriers
|
|
or pname:pImageMemoryBarriers must: not have any access flag included in
|
|
its pname:dstAccessMask member if that bit is not supported by any of
|
|
the pipeline stages in pname:dstStageMask, as specified in the
|
|
<<synchronization-access-types-supported, table of supported access
|
|
types>>.
|
|
****
|
|
|
|
include::../validity/protos/vkCmdPipelineBarrier.txt[]
|
|
|
|
|
|
[[synchronization-pipeline-barriers-subpass-self-dependencies]]
|
|
=== Subpass Self-dependency
|
|
|
|
If fname:vkCmdPipelineBarrier is called inside a render pass instance, the
|
|
following restrictions apply.
|
|
For a given subpass to allow a pipeline barrier, the render pass must:
|
|
declare a _self-dependency_ from that subpass to itself.
|
|
That is, there must: exist a sname:VkSubpassDependency in the subpass
|
|
dependency list for the render pass with pname:srcSubpass and
|
|
pname:dstSubpass equal to that subpass index.
|
|
More than one self-dependency can: be declared for each subpass.
|
|
Self-dependencies must: only include pipeline stage bits that are graphics
|
|
stages.
|
|
Self-dependencies must: not have any earlier pipeline stages depend on any
|
|
later pipeline stages.
|
|
More precisely, this means that whatever is the last pipeline stage in
|
|
pname:srcStageMask must: be no later than whatever is the first pipeline
|
|
stage in pname:dstStageMask (the latest source stage can: be equal to the
|
|
earliest destination stage).
|
|
If the source and destination stage masks both include framebuffer-space
|
|
stages, then pname:dependencyFlags must: include
|
|
ename:VK_DEPENDENCY_BY_REGION_BIT.
|
|
|
|
A fname:vkCmdPipelineBarrier command inside a render pass instance must: be
|
|
a _subset_ of one of the self-dependencies of the subpass it is used in,
|
|
meaning that the stage masks and access masks must: each include only a
|
|
subset of the bits of the corresponding mask in that self-dependency.
|
|
If the self-dependency has ename:VK_DEPENDENCY_BY_REGION_BIT set, then so
|
|
must: the pipeline barrier.
|
|
Pipeline barriers within a render pass instance can: only be types
|
|
sname:VkMemoryBarrier or sname:VkImageMemoryBarrier.
|
|
If a sname:VkImageMemoryBarrier is used, the image and image subresource
|
|
range specified in the barrier must: be a subset of one of the image views
|
|
used by the framebuffer in the current subpass.
|
|
Additionally, pname:oldLayout must: be equal to pname:newLayout, and both
|
|
the pname:srcQueueFamilyIndex and pname:dstQueueFamilyIndex must: be
|
|
ename:VK_QUEUE_FAMILY_IGNORED.
|
|
|
|
|
|
[[synchronization-memory-barriers]]
|
|
== Memory Barriers
|
|
|
|
_Memory barriers_ are used to explicitly control access to buffer and image
|
|
subresource ranges.
|
|
Memory barriers are used to <<synchronization-queue-transfers, transfer
|
|
ownership between queue families>>,
|
|
<<synchronization-image-layout-transitions, change image layouts>>, and
|
|
define <<synchronization-dependencies-available-and-visible, availability
|
|
and visibility operations>>.
|
|
They explicitly define the <<synchronization-access-types, access types>>
|
|
and buffer and image subresource ranges that are included in the
|
|
<<synchronization-dependencies-access-scopes, access scopes>> of a memory
|
|
dependency that is created by a synchronization command that includes them.
|
|
|
|
[[synchronization-global-memory-barriers]]
|
|
=== Global Memory Barriers
|
|
|
|
Global memory barriers apply to memory accesses involving all memory objects
|
|
that exist at the time of its execution.
|
|
|
|
// refBegin VkMemoryBarrier Structure specifying a global memory barrier
|
|
|
|
The sname:VkMemoryBarrier structure is defined as:
|
|
|
|
include::../api/structs/VkMemoryBarrier.txt[]
|
|
|
|
* pname:sType is the type of this structure.
|
|
* pname:pNext is `NULL` or a pointer to an extension-specific structure.
|
|
* pname:srcAccessMask defines a <<synchronization-access-masks, source
|
|
access mask>>.
|
|
* pname:dstAccessMask defines a <<synchronization-access-masks,
|
|
destination access mask>>.
|
|
|
|
The first <<synchronization-dependencies-access-scopes, access scope>> is
|
|
limited to access types in the <<synchronization-access-masks, source access
|
|
mask>> specified by pname:srcAccessMask.
|
|
|
|
The second <<synchronization-dependencies-access-scopes, access scope>> is
|
|
limited to access types in the <<synchronization-access-masks, destination
|
|
access mask>> specified by pname:dstAccessMask.
|
|
|
|
include::../validity/structs/VkMemoryBarrier.txt[]
|
|
|
|
|
|
|
|
[[synchronization-buffer-memory-barriers]]
|
|
=== Buffer Memory Barriers
|
|
|
|
Buffer memory barriers only apply to memory accesses involving a specific
|
|
buffer range.
|
|
That is, a memory dependency formed from an buffer memory barrier is
|
|
<<synchronization-dependencies-access-scopes, scoped>> to access via the
|
|
specified buffer range.
|
|
Buffer memory barriers can: also be used to define a
|
|
<<synchronization-queue-transfers, queue family ownership transfer>> for the
|
|
specified buffer range.
|
|
|
|
// refBegin VkBufferMemoryBarrier Structure specifying a buffer memory barrier
|
|
|
|
The sname:VkBufferMemoryBarrier structure is defined as:
|
|
|
|
include::../api/structs/VkBufferMemoryBarrier.txt[]
|
|
|
|
* pname:sType is the type of this structure.
|
|
* pname:pNext is `NULL` or a pointer to an extension-specific structure.
|
|
* pname:srcAccessMask defines a <<synchronization-access-masks, source
|
|
access mask>>.
|
|
* pname:dstAccessMask defines a <<synchronization-access-masks,
|
|
destination access mask>>.
|
|
* pname:srcQueueFamilyIndex is the source queue family for a
|
|
<<synchronization-queue-transfers, queue family ownership transfer>>.
|
|
* pname:dstQueueFamilyIndex is the destination queue family for a
|
|
<<synchronization-queue-transfers, queue family ownership transfer>>.
|
|
* pname:buffer is a handle to the buffer whose backing memory is affected
|
|
by the barrier.
|
|
* pname:offset is an offset in bytes into the backing memory for
|
|
pname:buffer; this is relative to the base offset as bound to the buffer
|
|
(see flink:vkBindBufferMemory).
|
|
* pname:size is a size in bytes of the affected area of backing memory for
|
|
pname:buffer, or ename:VK_WHOLE_SIZE to use the range from pname:offset
|
|
to the end of the buffer.
|
|
|
|
The first <<synchronization-dependencies-access-scopes, access scope>> is
|
|
limited to access to memory through the specified buffer range, via access
|
|
types in the <<synchronization-access-masks, source access mask>> specified
|
|
by pname:srcAccessMask.
|
|
If pname:srcAccessMask includes ename:VK_ACCESS_HOST_WRITE_BIT, memory
|
|
writes performed by that access type are also made visible, as that access
|
|
type is not performed through a resource.
|
|
|
|
The second <<synchronization-dependencies-access-scopes, access scope>> is
|
|
limited to access to memory through the specified buffer range, via access
|
|
types in the <<synchronization-access-masks, destination access mask>>
|
|
specified by pname:dstAccessMask.
|
|
If pname:dstAccessMask includes ename:VK_ACCESS_HOST_WRITE_BIT or
|
|
ename:VK_ACCESS_HOST_READ_BIT, available memory writes are also made visible
|
|
to accesses of those types, as those access types are not performed through
|
|
a resource.
|
|
|
|
If pname:srcQueueFamilyIndex is not equal to pname:dstQueueFamilyIndex, and
|
|
pname:srcQueueFamilyIndex is equal to the current queue family, then the
|
|
memory barrier defines a <<synchronization-queue-transfers-release, queue
|
|
family release operation>> for the specified buffer range, and the second
|
|
access scope includes no access, as if pname:dstAccessMask was `0`.
|
|
|
|
If pname:dstQueueFamilyIndex is not equal to pname:srcQueueFamilyIndex, and
|
|
pname:dstQueueFamilyIndex is equal to the current queue family, then the
|
|
memory barrier defines a <<synchronization-queue-transfers-acquire, queue
|
|
family acquire operation>> for the specified buffer range, and the first
|
|
access scope includes no access, as if pname:srcAccessMask was `0`.
|
|
|
|
.Valid Usage
|
|
****
|
|
* pname:offset must: be less than the size of pname:buffer
|
|
* If pname:size is not equal to ename:VK_WHOLE_SIZE, pname:size must: be
|
|
greater than `0`
|
|
* If pname:size is not equal to ename:VK_WHOLE_SIZE, pname:size must: be
|
|
less than or equal to than the size of pname:buffer minus pname:offset
|
|
* If pname:buffer was created with a sharing mode of
|
|
ename:VK_SHARING_MODE_CONCURRENT, pname:srcQueueFamilyIndex and
|
|
pname:dstQueueFamilyIndex must: both be ename:VK_QUEUE_FAMILY_IGNORED
|
|
* If pname:buffer was created with a sharing mode of
|
|
ename:VK_SHARING_MODE_EXCLUSIVE, pname:srcQueueFamilyIndex and
|
|
pname:dstQueueFamilyIndex must: either both be
|
|
ename:VK_QUEUE_FAMILY_IGNORED, or both be a valid queue family (see
|
|
<<devsandqueues-queueprops>>)
|
|
* If pname:buffer was created with a sharing mode of
|
|
ename:VK_SHARING_MODE_EXCLUSIVE, and pname:srcQueueFamilyIndex and
|
|
pname:dstQueueFamilyIndex are valid queue families, at least one of them
|
|
must: be the same as the family of the queue that will execute this
|
|
barrier
|
|
****
|
|
|
|
include::../validity/structs/VkBufferMemoryBarrier.txt[]
|
|
|
|
|
|
[[synchronization-image-memory-barriers]]
|
|
=== Image Memory Barriers
|
|
|
|
Image memory barriers only apply to memory accesses involving a specific
|
|
image subresource range.
|
|
That is, a memory dependency formed from an image memory barrier is
|
|
<<synchronization-dependencies-access-scopes, scoped>> to access via the
|
|
specified image subresource range.
|
|
Image memory barriers can: also be used to define
|
|
<<synchronization-image-layout-transitions, image layout transitions>> or a
|
|
<<synchronization-queue-transfers, queue family ownership transfer>> for the
|
|
specified image subresource range.
|
|
|
|
// refBegin VkImageMemoryBarrier Structure specifying the parameters of an image memory barrier
|
|
|
|
The sname:VkImageMemoryBarrier structure is defined as:
|
|
|
|
include::../api/structs/VkImageMemoryBarrier.txt[]
|
|
|
|
* pname:sType is the type of this structure.
|
|
* pname:pNext is `NULL` or a pointer to an extension-specific structure.
|
|
* pname:srcAccessMask defines a <<synchronization-access-masks, source
|
|
access mask>>.
|
|
* pname:dstAccessMask defines a <<synchronization-access-masks,
|
|
destination access mask>>.
|
|
* pname:oldLayout is the old layout in an
|
|
<<synchronization-image-layout-transitions, image layout transition>>.
|
|
* pname:newLayout is the new layout in an
|
|
<<synchronization-image-layout-transitions, image layout transition>>.
|
|
* pname:srcQueueFamilyIndex is the source queue family for a
|
|
<<synchronization-queue-transfers, queue family ownership transfer>>.
|
|
* pname:dstQueueFamilyIndex is the destination queue family for a
|
|
<<synchronization-queue-transfers, queue family ownership transfer>>.
|
|
* pname:image is a handle to the image affected by this barrier.
|
|
* pname:subresourceRange describes the <<resources-image-views, image
|
|
subresource range>> within pname:image that is affected by this barrier.
|
|
|
|
The first <<synchronization-dependencies-access-scopes, access scope>> is
|
|
limited to access to memory through the specified image subresource range,
|
|
via access types in the <<synchronization-access-masks, source access mask>>
|
|
specified by pname:srcAccessMask.
|
|
If pname:srcAccessMask includes ename:VK_ACCESS_HOST_WRITE_BIT, memory
|
|
writes performed by that access type are also made visible, as that access
|
|
type is not performed through a resource.
|
|
|
|
The second <<synchronization-dependencies-access-scopes, access scope>> is
|
|
limited to access to memory through the specified image subresource range,
|
|
via access types in the <<synchronization-access-masks, destination access
|
|
mask>> specified by pname:dstAccessMask.
|
|
If pname:dstAccessMask includes ename:VK_ACCESS_HOST_WRITE_BIT or
|
|
ename:VK_ACCESS_HOST_READ_BIT, available memory writes are also made visible
|
|
to accesses of those types, as those access types are not performed through
|
|
a resource.
|
|
|
|
If pname:srcQueueFamilyIndex is not equal to pname:dstQueueFamilyIndex, and
|
|
pname:srcQueueFamilyIndex is equal to the current queue family, then the
|
|
memory barrier defines a <<synchronization-queue-transfers-release, queue
|
|
family release operation>> for the specified image subresource range, and
|
|
the second access scope includes no access, as if pname:dstAccessMask was
|
|
`0`.
|
|
|
|
If pname:dstQueueFamilyIndex is not equal to pname:srcQueueFamilyIndex, and
|
|
pname:dstQueueFamilyIndex is equal to the current queue family, then the
|
|
memory barrier defines a <<synchronization-queue-transfers-acquire, queue
|
|
family acquire operation>> for the specified image subresource range, and
|
|
the first access scope includes no access, as if pname:srcAccessMask was
|
|
`0`.
|
|
|
|
If pname:oldLayout is not equal to pname:newLayout, then the memory barrier
|
|
defines an <<synchronization-image-layout-transitions, image layout
|
|
transition>> for the specified image subresource range.
|
|
|
|
[[synchronization-image-barrier-layout-transition-order]]
|
|
Layout transitions that are performed via image memory barriers execute in
|
|
their entirety in <<synchronization-submission-order, submission order>>,
|
|
relative to other image layout transitions submitted to the same queue,
|
|
including those performed by <<renderpass, render passes>>.
|
|
In effect there is an implicit execution dependency from each such layout
|
|
transition to all layout transitions previously submitted to the same queue.
|
|
|
|
.Valid Usage
|
|
****
|
|
* pname:oldLayout must: be ename:VK_IMAGE_LAYOUT_UNDEFINED or the current
|
|
layout of the image subresources affected by the barrier
|
|
* pname:newLayout must: not be ename:VK_IMAGE_LAYOUT_UNDEFINED or
|
|
ename:VK_IMAGE_LAYOUT_PREINITIALIZED
|
|
* If pname:image was created with a sharing mode of
|
|
ename:VK_SHARING_MODE_CONCURRENT, pname:srcQueueFamilyIndex and
|
|
pname:dstQueueFamilyIndex must: both be ename:VK_QUEUE_FAMILY_IGNORED
|
|
* If pname:image was created with a sharing mode of
|
|
ename:VK_SHARING_MODE_EXCLUSIVE, pname:srcQueueFamilyIndex and
|
|
pname:dstQueueFamilyIndex must: either both be
|
|
ename:VK_QUEUE_FAMILY_IGNORED, or both be a valid queue family (see
|
|
<<devsandqueues-queueprops>>)
|
|
* If pname:image was created with a sharing mode of
|
|
ename:VK_SHARING_MODE_EXCLUSIVE, and pname:srcQueueFamilyIndex and
|
|
pname:dstQueueFamilyIndex are valid queue families, at least one of them
|
|
must: be the same as the family of the queue that will execute this
|
|
barrier
|
|
* pname:subresourceRange must: be a valid image subresource range for the
|
|
image (see <<resources-image-views>>)
|
|
* If pname:image has a depth/stencil format with both depth and stencil
|
|
components, then pname:aspectMask member of pname:subresourceRange must:
|
|
include both ename:VK_IMAGE_ASPECT_DEPTH_BIT and
|
|
ename:VK_IMAGE_ASPECT_STENCIL_BIT
|
|
* If either pname:oldLayout or pname:newLayout is
|
|
ename:VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL then pname:image must:
|
|
have been created with ename:VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT set
|
|
* If either pname:oldLayout or pname:newLayout is
|
|
ename:VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL then pname:image
|
|
must: have been created with
|
|
ename:VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT set
|
|
* If either pname:oldLayout or pname:newLayout is
|
|
ename:VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL then pname:image
|
|
must: have been created with
|
|
ename:VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT set
|
|
* If either pname:oldLayout or pname:newLayout is
|
|
ename:VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL then pname:image must:
|
|
have been created with ename:VK_IMAGE_USAGE_SAMPLED_BIT or
|
|
ename:VK_IMAGE_USAGE_INPUT_ATTACHMENT_BIT set
|
|
* If either pname:oldLayout or pname:newLayout is
|
|
ename:VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL then pname:image must: have
|
|
been created with ename:VK_IMAGE_USAGE_TRANSFER_SRC_BIT set
|
|
* If either pname:oldLayout or pname:newLayout is
|
|
ename:VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL then pname:image must: have
|
|
been created with ename:VK_IMAGE_USAGE_TRANSFER_DST_BIT set
|
|
****
|
|
|
|
include::../validity/structs/VkImageMemoryBarrier.txt[]
|
|
|
|
|
|
[[synchronization-queue-transfers]]
|
|
=== Queue Family Ownership Transfer
|
|
|
|
Resources created with a elink:VkSharingMode of
|
|
ename:VK_SHARING_MODE_EXCLUSIVE must: have their ownership explicitly
|
|
transferred from one queue family to another in order to access their
|
|
content in a well-defined manner on a queue in a different queue family.
|
|
If memory dependencies are correctly expressed between uses of such a
|
|
resource between two queues in different families, but no ownership transfer
|
|
is defined, the contents of that resource are undefined for any read
|
|
accesses performed by the second queue family.
|
|
|
|
.Note
|
|
[NOTE]
|
|
====
|
|
If an application does not need the contents of a resource to remain valid
|
|
when transferring from one queue family to another, then the ownership
|
|
transfer should: be skipped.
|
|
====
|
|
|
|
A queue family ownership transfer consists of two distinct parts:
|
|
|
|
. Release exclusive ownership from the source queue family
|
|
. Acquire exclusive ownership for the destination queue family
|
|
|
|
An application must: ensure that these operations occur in the correct order
|
|
by defining an execution dependency between them, e.g. using a semaphore.
|
|
|
|
[[synchronization-queue-transfers-release]] A _release operation_ is used to
|
|
release exclusive ownership of a range of a buffer or image subresource
|
|
range.
|
|
A release operation is defined by executing a
|
|
<<synchronization-buffer-memory-barriers, buffer memory barrier>> (for a
|
|
buffer range) or an <<synchronization-image-memory-barriers, image memory
|
|
barrier>> (for an image subresource range), on a queue from the source queue
|
|
family.
|
|
The pname:srcQueueFamilyIndex parameter of the barrier must: be set to the
|
|
source queue family index, and the pname:dstQueueFamilyIndex parameter to
|
|
the destination queue family index.
|
|
pname:dstStageMask is ignored for such a barrier, such that no visibility
|
|
operation is executed - the value of this mask does not affect the validity
|
|
of the barrier.
|
|
The release operation happens-after the availability operation.
|
|
|
|
[[synchronization-queue-transfers-acquire]] An _acquire operation_ is used
|
|
to acquire exclusive ownership of a range of a buffer or image subresource
|
|
range.
|
|
An acquire operation is defined by executing a
|
|
<<synchronization-buffer-memory-barriers, buffer memory barrier>> (for a
|
|
buffer range) or an <<synchronization-image-memory-barriers, image memory
|
|
barrier>> (for an image subresource range), on a queue from the destination
|
|
queue family.
|
|
The pname:srcQueueFamilyIndex parameter of the barrier must: be set to the
|
|
source queue family index, and the pname:dstQueueFamilyIndex parameter to
|
|
the destination queue family index.
|
|
pname:srcStageMask is ignored for such a barrier, such that no availability
|
|
operation is executed - the value of this mask does not affect the validity
|
|
of the barrier.
|
|
The acquire operation happens-before the visibility operation.
|
|
|
|
.Note
|
|
[NOTE]
|
|
====
|
|
Whilst it is not invalid to provide destination or source access masks for
|
|
memory barriers used for release or acquire operations, respectively, they
|
|
have no practical effect.
|
|
Access after a release operation has undefined results, and so visibility
|
|
for those accesses has no practical effect.
|
|
Similarly, write access before an acquire operation will produce undefined
|
|
results for future access, so availability of those writes has no practical
|
|
use.
|
|
In an earlier version of the specification, these were required to match on
|
|
both sides - but this was subsequently relaxed.
|
|
It is now recommended that these masks are simply set to 0.
|
|
====
|
|
|
|
If the transfer is via an image memory barrier, and an
|
|
<<synchronization-image-layout-transitions, image layout transition>> is
|
|
desired, then the values of pname:oldLayout and pname:newLayout in the
|
|
release memory barrier must: be equal to values of pname:oldLayout and
|
|
pname:newLayout in the acquire memory barrier.
|
|
Although the image layout transition is submitted twice, it will only be
|
|
executed once.
|
|
A layout transition specified in this way happens-after the release
|
|
operation and happens-before the acquire operation.
|
|
|
|
If the values of pname:srcQueueFamilyIndex and pname:dstQueueFamilyIndex are
|
|
equal, no ownership transfer is performed, and the barrier operates as if
|
|
they were both set to ename:VK_QUEUE_FAMILY_IGNORED.
|
|
|
|
Queue family ownership transfers may: perform read and write accesses on all
|
|
memory bound to the image subresource or buffer range, so applications must:
|
|
ensure that all memory writes have been made
|
|
<<synchronization-dependencies-available-and-visible, available>> before a
|
|
queue family ownership transfer is executed.
|
|
Available memory is automatically made visible to queue family release and
|
|
acquire operations, and writes performed by those operations are
|
|
automatically made available.
|
|
|
|
Once a queue family has acquired ownership of a buffer range or image
|
|
subresource range of an ename:VK_SHARING_MODE_EXCLUSIVE resource, its
|
|
contents are undefined to other queue families unless ownership is
|
|
transferred.
|
|
The contents of any portion of another resource which aliases memory that is
|
|
bound to the transferred buffer or image subresource range are undefined
|
|
after a release or acquire operation.
|
|
|
|
|
|
[[synchronization-wait-idle]]
|
|
== Wait Idle Operations
|
|
|
|
// refBegin vkQueueWaitIdle Wait for a queue to become idle
|
|
|
|
To wait on the host for the completion of outstanding queue operations for a
|
|
given queue, call:
|
|
|
|
include::../api/protos/vkQueueWaitIdle.txt[]
|
|
|
|
* pname:queue is the queue on which to wait.
|
|
|
|
fname:vkQueueWaitIdle is equivalent to submitting a fence to a queue and
|
|
waiting with an infinite timeout for that fence to signal.
|
|
|
|
include::../validity/protos/vkQueueWaitIdle.txt[]
|
|
|
|
// refBegin vkDeviceWaitIdle Wait for a device to become idle
|
|
|
|
To wait on the host for the completion of outstanding queue operations for
|
|
all queues on a given logical device, call:
|
|
|
|
include::../api/protos/vkDeviceWaitIdle.txt[]
|
|
|
|
* pname:device is the logical device to idle.
|
|
|
|
fname:vkDeviceWaitIdle is equivalent to calling fname:vkQueueWaitIdle for
|
|
all queues owned by pname:device.
|
|
|
|
include::../validity/protos/vkDeviceWaitIdle.txt[]
|
|
|
|
|
|
[[synchronization-submission-host-writes]]
|
|
== Host Write Ordering Guarantees
|
|
|
|
When batches of command buffers are submitted to a queue via
|
|
flink:vkQueueSubmit, it defines a memory dependency with prior host
|
|
operations, and execution of command buffers submitted to the queue.
|
|
|
|
The first <<synchronization-dependencies-scopes, synchronization scope>> is
|
|
defined by the host execution model, but includes execution of
|
|
flink:vkQueueSubmit on the host and anything that happened-before it.
|
|
|
|
The second <<synchronization-dependencies-scopes, synchronization scope>>
|
|
includes every command submitted in the same <<devsandqueues-submission,
|
|
queue submission>> command, and all future submissions to the same queue.
|
|
|
|
The first <<synchronization-dependencies-access-scopes, access scope>>
|
|
includes all host writes to mappable device memory that are either coherent,
|
|
or have been flushed with flink:vkFlushMappedMemoryRanges.
|
|
|
|
The second <<synchronization-dependencies-access-scopes, access scope>>
|
|
includes all memory access performed by the device.
|