Package org.lwjgl.vulkan

Class EXTSubgroupSizeControl

java.lang.Object

org.lwjgl.vulkan.EXTSubgroupSizeControl

public final class EXTSubgroupSizeControl
extends java.lang.Object

Short Description

Enables an implementation to control the subgroup size by allowing a varying subgroup size and also specifying a required subgroup size.

Description

This extension extends the subgroup support in Vulkan 1.1 to allow an implementation to expose a varying subgroup size. Previously Vulkan exposed a single subgroup size per physical device, with the expectation that implementations will behave as if all subgroups have the same size. Some implementations may dispatch shaders with a varying subgroup size for different subgroups. As a result they could implicitly split a large subgroup into smaller subgroups or represent a small subgroup as a larger subgroup, some of whose invocations were inactive on launch.

To aid developers in understanding the performance characteristics of their programs, this extension exposes a minimum and maximum subgroup size that a physical device supports and a pipeline create flag to enable that pipeline to vary its subgroup size. If enabled, any SubgroupSize decorated variables in the SPIR-V shader modules provided to pipeline creation may vary between the minimum and maximum subgroup sizes.

An implementation is also optionally allowed to support specifying a required subgroup size for a given pipeline stage. Implementations advertise which stages support a required subgroup size, and any pipeline of a supported stage can be passed a VkPipelineShaderStageRequiredSubgroupSizeCreateInfoEXT structure to set the subgroup size for that shader stage of the pipeline. For compute shaders, this requires the developer to query the maxComputeWorkgroupSubgroups and ensure that:

s = {WorkGroupSize.x * WorkGroupSize.y * WorkgroupSize.z ≤ SubgroupSize * maxComputeWorkgroupSubgroups }

Developers can also specify a new pipeline shader stage create flag that requires the implementation to have fully populated subgroups within local workgroups. This requires the workgroup size in the X dimension to be a multiple of the subgroup size.

Name String

VK_EXT_subgroup_size_control

Extension Type

Device extension

Registered Extension Number

226

Revision

2

Extension and Version Dependencies

• Requires Vulkan 1.1

Contact

• Neil Henning sheredom

Last Modified Date

2019-03-05

Contributors

• Jeff Bolz, NVIDIA
• Jason Ekstrand, Intel
• Sławek Grajewski, Intel
• Jesse Hall, Google
• Neil Henning, AMD
• Daniel Koch, NVIDIA
• Jeff Leger, Qualcomm
• Graeme Leese, Broadcom
• Allan MacKinnon, Google
• Mariusz Merecki, Intel
• Graham Wihlidal, Electronic Arts

Field Summary

Fields

Modifier and Type	Field	Description
static java.lang.String	VK_EXT_SUBGROUP_SIZE_CONTROL_EXTENSION_NAME	The extension name.
static int	VK_EXT_SUBGROUP_SIZE_CONTROL_SPEC_VERSION	The extension specification version.
static int	VK_PIPELINE_SHADER_STAGE_CREATE_ALLOW_VARYING_SUBGROUP_SIZE_BIT_EXT VK_PIPELINE_SHADER_STAGE_CREATE_REQUIRE_FULL_SUBGROUPS_BIT_EXT	Extends VkPipelineShaderStageCreateFlagBits.
static int	VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_SUBGROUP_SIZE_CONTROL_FEATURES_EXT VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_SUBGROUP_SIZE_CONTROL_PROPERTIES_EXT VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_REQUIRED_SUBGROUP_SIZE_CREATE_INFO_EXT	Extends VkStructureType.

Method Summary

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

VK_EXT_SUBGROUP_SIZE_CONTROL_SPEC_VERSION

The extension specification version.

VK_EXT_SUBGROUP_SIZE_CONTROL_EXTENSION_NAME

The extension name.

VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_SUBGROUP_SIZE_CONTROL_PROPERTIES_EXT, VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_REQUIRED_SUBGROUP_SIZE_CREATE_INFO_EXT, VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_SUBGROUP_SIZE_CONTROL_FEATURES_EXT

Extends VkStructureType.

Enum values:

• STRUCTURE_TYPE_PHYSICAL_DEVICE_SUBGROUP_SIZE_CONTROL_PROPERTIES_EXT
• STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_REQUIRED_SUBGROUP_SIZE_CREATE_INFO_EXT
• STRUCTURE_TYPE_PHYSICAL_DEVICE_SUBGROUP_SIZE_CONTROL_FEATURES_EXT

VK_PIPELINE_SHADER_STAGE_CREATE_ALLOW_VARYING_SUBGROUP_SIZE_BIT_EXT, VK_PIPELINE_SHADER_STAGE_CREATE_REQUIRE_FULL_SUBGROUPS_BIT_EXT

Extends VkPipelineShaderStageCreateFlagBits.

Enum values:

• PIPELINE_SHADER_STAGE_CREATE_ALLOW_VARYING_SUBGROUP_SIZE_BIT_EXT
• PIPELINE_SHADER_STAGE_CREATE_REQUIRE_FULL_SUBGROUPS_BIT_EXT