## 28. Dispatching Commands

Dispatching commands (commands with Dispatch in the name) provoke work in a compute pipeline. Dispatching commands are recorded into a command buffer and when executed by a queue, will produce work which executes according to the bound compute pipeline. A compute pipeline must be bound to a command buffer before any dispatching commands are recorded in that command buffer.

To record a dispatch, call:

// Provided by VK_VERSION_1_0
void vkCmdDispatch(
VkCommandBuffer                             commandBuffer,
uint32_t                                    groupCountX,
uint32_t                                    groupCountY,
uint32_t                                    groupCountZ);
• commandBuffer is the command buffer into which the command will be recorded.

• groupCountX is the number of local workgroups to dispatch in the X dimension.

• groupCountY is the number of local workgroups to dispatch in the Y dimension.

• groupCountZ is the number of local workgroups to dispatch in the Z dimension.

When the command is executed, a global workgroup consisting of groupCountX × groupCountY × groupCountZ local workgroups is assembled.

Valid Usage
• VUID-vkCmdDispatch-magFilter-04553
If a VkSampler created with magFilter or minFilter equal to VK_FILTER_LINEAR and compareEnable equal to VK_FALSE is used to sample a VkImageView as a result of this command, then the image view’s format features must contain VK_FORMAT_FEATURE_SAMPLED_IMAGE_FILTER_LINEAR_BIT

• VUID-vkCmdDispatch-mipmapMode-04770
If a VkSampler created with mipmapMode equal to VK_SAMPLER_MIPMAP_MODE_LINEAR and compareEnable equal to VK_FALSE is used to sample a VkImageView as a result of this command, then the image view’s format features must contain VK_FORMAT_FEATURE_SAMPLED_IMAGE_FILTER_LINEAR_BIT

• VUID-vkCmdDispatch-None-02691
If a VkImageView is accessed using atomic operations as a result of this command, then the image view’s format features must contain VK_FORMAT_FEATURE_STORAGE_IMAGE_ATOMIC_BIT

• VUID-vkCmdDispatch-None-02697
For each set n that is statically used by the VkPipeline bound to the pipeline bind point used by this command, a descriptor set must have been bound to n at the same pipeline bind point, with a VkPipelineLayout that is compatible for set n, with the VkPipelineLayout used to create the current VkPipeline, as described in Pipeline Layout Compatibility

• VUID-vkCmdDispatch-None-02698
For each push constant that is statically used by the VkPipeline bound to the pipeline bind point used by this command, a push constant value must have been set for the same pipeline bind point, with a VkPipelineLayout that is compatible for push constants, with the VkPipelineLayout used to create the current VkPipeline, as described in Pipeline Layout Compatibility

• VUID-vkCmdDispatch-None-02699
Descriptors in each bound descriptor set, specified via vkCmdBindDescriptorSets, must be valid if they are statically used by the VkPipeline bound to the pipeline bind point used by this command

• VUID-vkCmdDispatch-None-02700
A valid pipeline must be bound to the pipeline bind point used by this command

• VUID-vkCmdDispatch-commandBuffer-02701
If the VkPipeline object bound to the pipeline bind point used by this command requires any dynamic state, that state must have been set or inherited (if the VK_NV_inherited_viewport_scissor extension is enabled) for commandBuffer, and done so after any previously bound pipeline with the corresponding state not specified as dynamic

• VUID-vkCmdDispatch-None-02859
There must not have been any calls to dynamic state setting commands for any state not specified as dynamic in the VkPipeline object bound to the pipeline bind point used by this command, since that pipeline was bound

• VUID-vkCmdDispatch-None-02702
If the VkPipeline object bound to the pipeline bind point used by this command accesses a VkSampler object that uses unnormalized coordinates, that sampler must not be used to sample from any VkImage with a VkImageView of the type VK_IMAGE_VIEW_TYPE_3D, VK_IMAGE_VIEW_TYPE_CUBE, VK_IMAGE_VIEW_TYPE_1D_ARRAY, VK_IMAGE_VIEW_TYPE_2D_ARRAY or VK_IMAGE_VIEW_TYPE_CUBE_ARRAY, in any shader stage

• VUID-vkCmdDispatch-None-02703
If the VkPipeline object bound to the pipeline bind point used by this command accesses a VkSampler object that uses unnormalized coordinates, that sampler must not be used with any of the SPIR-V OpImageSample* or OpImageSparseSample* instructions with ImplicitLod, Dref or Proj in their name, in any shader stage

• VUID-vkCmdDispatch-None-02704
If the VkPipeline object bound to the pipeline bind point used by this command accesses a VkSampler object that uses unnormalized coordinates, that sampler must not be used with any of the SPIR-V OpImageSample* or OpImageSparseSample* instructions that includes a LOD bias or any offset values, in any shader stage

• VUID-vkCmdDispatch-None-02705
If the robust buffer access feature is not enabled, and if the VkPipeline object bound to the pipeline bind point used by this command accesses a uniform buffer, it must not access values outside of the range of the buffer as specified in the descriptor set bound to the same pipeline bind point

• VUID-vkCmdDispatch-None-02706
If the robust buffer access feature is not enabled, and if the VkPipeline object bound to the pipeline bind point used by this command accesses a storage buffer, it must not access values outside of the range of the buffer as specified in the descriptor set bound to the same pipeline bind point

• VUID-vkCmdDispatch-None-04115
If a VkImageView is accessed using OpImageWrite as a result of this command, then the Type of the Texel operand of that instruction must have at least as many components as the image view’s format

• VUID-vkCmdDispatch-OpImageWrite-04469
If a VkBufferView is accessed using OpImageWrite as a result of this command, then the Type of the Texel operand of that instruction must have at least as many components as the buffer view’s format

• VUID-vkCmdDispatch-groupCountX-00386
groupCountX must be less than or equal to VkPhysicalDeviceLimits::maxComputeWorkGroupCount[0]

• VUID-vkCmdDispatch-groupCountY-00387
groupCountY must be less than or equal to VkPhysicalDeviceLimits::maxComputeWorkGroupCount[1]

• VUID-vkCmdDispatch-groupCountZ-00388
groupCountZ must be less than or equal to VkPhysicalDeviceLimits::maxComputeWorkGroupCount[2]

Valid Usage (Implicit)
• VUID-vkCmdDispatch-commandBuffer-parameter
commandBuffer must be a valid VkCommandBuffer handle

• VUID-vkCmdDispatch-commandBuffer-recording
commandBuffer must be in the recording state

• VUID-vkCmdDispatch-commandBuffer-cmdpool
The VkCommandPool that commandBuffer was allocated from must support compute operations

• VUID-vkCmdDispatch-renderpass
This command must only be called outside of a render pass instance

Host Synchronization
• Host access to commandBuffer must be externally synchronized

• Host access to the VkCommandPool that commandBuffer was allocated from must be externally synchronized

Command Properties
Command Buffer Levels Render Pass Scope Supported Queue Types

Primary
Secondary

Outside

Compute

To record an indirect dispatching command, call:

// Provided by VK_VERSION_1_0
void vkCmdDispatchIndirect(
VkCommandBuffer                             commandBuffer,
VkBuffer                                    buffer,
VkDeviceSize                                offset);
• commandBuffer is the command buffer into which the command will be recorded.

• buffer is the buffer containing dispatch parameters.

• offset is the byte offset into buffer where parameters begin.

vkCmdDispatchIndirect behaves similarly to vkCmdDispatch except that the parameters are read by the device from a buffer during execution. The parameters of the dispatch are encoded in a VkDispatchIndirectCommand structure taken from buffer starting at offset.

Valid Usage
• VUID-vkCmdDispatchIndirect-magFilter-04553
If a VkSampler created with magFilter or minFilter equal to VK_FILTER_LINEAR and compareEnable equal to VK_FALSE is used to sample a VkImageView as a result of this command, then the image view’s format features must contain VK_FORMAT_FEATURE_SAMPLED_IMAGE_FILTER_LINEAR_BIT

• VUID-vkCmdDispatchIndirect-mipmapMode-04770
If a VkSampler created with mipmapMode equal to VK_SAMPLER_MIPMAP_MODE_LINEAR and compareEnable equal to VK_FALSE is used to sample a VkImageView as a result of this command, then the image view’s format features must contain VK_FORMAT_FEATURE_SAMPLED_IMAGE_FILTER_LINEAR_BIT

• VUID-vkCmdDispatchIndirect-None-02691
If a VkImageView is accessed using atomic operations as a result of this command, then the image view’s format features must contain VK_FORMAT_FEATURE_STORAGE_IMAGE_ATOMIC_BIT

• VUID-vkCmdDispatchIndirect-None-02697
For each set n that is statically used by the VkPipeline bound to the pipeline bind point used by this command, a descriptor set must have been bound to n at the same pipeline bind point, with a VkPipelineLayout that is compatible for set n, with the VkPipelineLayout used to create the current VkPipeline, as described in Pipeline Layout Compatibility

• VUID-vkCmdDispatchIndirect-None-02698
For each push constant that is statically used by the VkPipeline bound to the pipeline bind point used by this command, a push constant value must have been set for the same pipeline bind point, with a VkPipelineLayout that is compatible for push constants, with the VkPipelineLayout used to create the current VkPipeline, as described in Pipeline Layout Compatibility

• VUID-vkCmdDispatchIndirect-None-02699
Descriptors in each bound descriptor set, specified via vkCmdBindDescriptorSets, must be valid if they are statically used by the VkPipeline bound to the pipeline bind point used by this command

• VUID-vkCmdDispatchIndirect-None-02700
A valid pipeline must be bound to the pipeline bind point used by this command

• VUID-vkCmdDispatchIndirect-commandBuffer-02701
If the VkPipeline object bound to the pipeline bind point used by this command requires any dynamic state, that state must have been set or inherited (if the VK_NV_inherited_viewport_scissor extension is enabled) for commandBuffer, and done so after any previously bound pipeline with the corresponding state not specified as dynamic

• VUID-vkCmdDispatchIndirect-None-02859
There must not have been any calls to dynamic state setting commands for any state not specified as dynamic in the VkPipeline object bound to the pipeline bind point used by this command, since that pipeline was bound

• VUID-vkCmdDispatchIndirect-None-02702
If the VkPipeline object bound to the pipeline bind point used by this command accesses a VkSampler object that uses unnormalized coordinates, that sampler must not be used to sample from any VkImage with a VkImageView of the type VK_IMAGE_VIEW_TYPE_3D, VK_IMAGE_VIEW_TYPE_CUBE, VK_IMAGE_VIEW_TYPE_1D_ARRAY, VK_IMAGE_VIEW_TYPE_2D_ARRAY or VK_IMAGE_VIEW_TYPE_CUBE_ARRAY, in any shader stage

• VUID-vkCmdDispatchIndirect-None-02703
If the VkPipeline object bound to the pipeline bind point used by this command accesses a VkSampler object that uses unnormalized coordinates, that sampler must not be used with any of the SPIR-V OpImageSample* or OpImageSparseSample* instructions with ImplicitLod, Dref or Proj in their name, in any shader stage

• VUID-vkCmdDispatchIndirect-None-02704
If the VkPipeline object bound to the pipeline bind point used by this command accesses a VkSampler object that uses unnormalized coordinates, that sampler must not be used with any of the SPIR-V OpImageSample* or OpImageSparseSample* instructions that includes a LOD bias or any offset values, in any shader stage

• VUID-vkCmdDispatchIndirect-None-02705
If the robust buffer access feature is not enabled, and if the VkPipeline object bound to the pipeline bind point used by this command accesses a uniform buffer, it must not access values outside of the range of the buffer as specified in the descriptor set bound to the same pipeline bind point

• VUID-vkCmdDispatchIndirect-None-02706
If the robust buffer access feature is not enabled, and if the VkPipeline object bound to the pipeline bind point used by this command accesses a storage buffer, it must not access values outside of the range of the buffer as specified in the descriptor set bound to the same pipeline bind point

• VUID-vkCmdDispatchIndirect-None-04115
If a VkImageView is accessed using OpImageWrite as a result of this command, then the Type of the Texel operand of that instruction must have at least as many components as the image view’s format

• VUID-vkCmdDispatchIndirect-OpImageWrite-04469
If a VkBufferView is accessed using OpImageWrite as a result of this command, then the Type of the Texel operand of that instruction must have at least as many components as the buffer view’s format

• VUID-vkCmdDispatchIndirect-buffer-02708
If buffer is non-sparse then it must be bound completely and contiguously to a single VkDeviceMemory object

• VUID-vkCmdDispatchIndirect-buffer-02709
buffer must have been created with the VK_BUFFER_USAGE_INDIRECT_BUFFER_BIT bit set

• VUID-vkCmdDispatchIndirect-offset-02710
offset must be a multiple of 4

• VUID-vkCmdDispatchIndirect-offset-00407
The sum of offset and the size of VkDispatchIndirectCommand must be less than or equal to the size of buffer

Valid Usage (Implicit)
• VUID-vkCmdDispatchIndirect-commandBuffer-parameter
commandBuffer must be a valid VkCommandBuffer handle

• VUID-vkCmdDispatchIndirect-buffer-parameter
buffer must be a valid VkBuffer handle

• VUID-vkCmdDispatchIndirect-commandBuffer-recording
commandBuffer must be in the recording state

• VUID-vkCmdDispatchIndirect-commandBuffer-cmdpool
The VkCommandPool that commandBuffer was allocated from must support compute operations

• VUID-vkCmdDispatchIndirect-renderpass
This command must only be called outside of a render pass instance

• VUID-vkCmdDispatchIndirect-commonparent
Both of buffer, and commandBuffer must have been created, allocated, or retrieved from the same VkDevice

Host Synchronization
• Host access to commandBuffer must be externally synchronized

• Host access to the VkCommandPool that commandBuffer was allocated from must be externally synchronized

Command Properties
Command Buffer Levels Render Pass Scope Supported Queue Types

Primary
Secondary

Outside

Compute

The VkDispatchIndirectCommand structure is defined as:

// Provided by VK_VERSION_1_0
typedef struct VkDispatchIndirectCommand {
uint32_t    x;
uint32_t    y;
uint32_t    z;
} VkDispatchIndirectCommand;
• x is the number of local workgroups to dispatch in the X dimension.

• y is the number of local workgroups to dispatch in the Y dimension.

• z is the number of local workgroups to dispatch in the Z dimension.

The members of VkDispatchIndirectCommand have the same meaning as the corresponding parameters of vkCmdDispatch.

Valid Usage
• VUID-VkDispatchIndirectCommand-x-00417
x must be less than or equal to VkPhysicalDeviceLimits::maxComputeWorkGroupCount[0]

• VUID-VkDispatchIndirectCommand-y-00418
y must be less than or equal to VkPhysicalDeviceLimits::maxComputeWorkGroupCount[1]

• VUID-VkDispatchIndirectCommand-z-00419
z must be less than or equal to VkPhysicalDeviceLimits::maxComputeWorkGroupCount[2]