Vulkan.Extensions.VK_QCOM_queue_perf_hint

vkQueueSetPerfHintQCOM - Set a performance hint on a queue

Valid Usage

• The queuePerfHint feature must be enabled

• queue must support at least one of the queue types specified in PhysicalDeviceQueuePerfHintPropertiesQCOM::supportedQueues

Valid Usage (Implicit)

• queue must be a valid Queue handle

• pPerfHintInfo must be a valid pointer to a valid PerfHintInfoQCOM structure

Host Synchronization

• Host access to queue must be externally synchronized if it was not created with DEVICE_QUEUE_CREATE_INTERNALLY_SYNCHRONIZED_BIT_KHR

Command Properties

'

Return Codes

Success

• SUCCESS

Failure

• ERROR_DEVICE_LOST

• ERROR_UNKNOWN

• ERROR_VALIDATION_FAILED

See Also

VK_QCOM_queue_perf_hint, PerfHintInfoQCOM, Queue

VkPerfHintInfoQCOM - Structure specifying the parameters used for setting a performance hint on a queue

Description

The device has two global frequency constraints, fmin and fmax, that can be influenced by the PERF_HINT_TYPE_FREQUENCY_MIN_QCOM, PERF_HINT_TYPE_FREQUENCY_MAX_QCOM, and PERF_HINT_TYPE_FREQUENCY_SCALED_QCOM performance hints. These constraints determine the range of clock frequencies that the platform performance algorithms may select from. If no constraints are set, fmin and fmax are set to the minimum and maximum frequencies the device can support, Fmin and Fmax respectively.

The fmin constraint applied by PERF_HINT_TYPE_FREQUENCY_SCALED_QCOM is calculated with the following:

• (f_{min} = lfloorfrac{scale}{100} times F_{max}rfloor)

The implementation rounds fmin down to the next available lower frequency the device supports, clamped to Fmin.

The global frequency constraints are determined by combining the performance hints from all of the device’s active queues of all processes on the host. Performance hints that influence device frequency are ranked, where a higher ranked hint supersedes all lower ranked hints. These are listed in order of highest rank to lowest:

• PERF_HINT_TYPE_FREQUENCY_MAX_QCOM

• PERF_HINT_TYPE_FREQUENCY_SCALED_QCOM and scale equal to 100

• PERF_HINT_TYPE_FREQUENCY_SCALED_QCOM and scale equal to 99

• PERF_HINT_TYPE_FREQUENCY_SCALED_QCOM and scale equal to 98

• …​

• PERF_HINT_TYPE_FREQUENCY_SCALED_QCOM and scale equal to 0

• PERF_HINT_TYPE_DEFAULT_QCOM

• PERF_HINT_TYPE_FREQUENCY_MIN_QCOM

This means that PERF_HINT_TYPE_FREQUENCY_MIN_QCOM only takes effect if all of the device’s other active queues running on the host also have the PERF_HINT_TYPE_FREQUENCY_MIN_QCOM hint applied.

If any queue is active that never had a performance hint applied and therefore is in the PERF_HINT_TYPE_DEFAULT_QCOM state, it will supersede in setting the constraints over PERF_HINT_TYPE_FREQUENCY_MIN_QCOM. This is necessary to avoid negatively impacting performance for normal queues while a low power queue is active.

Valid Usage

• If type is not PERF_HINT_TYPE_FREQUENCY_SCALED_QCOM, scale must equal 0

• scale must be less than or equal to 100

Valid Usage (Implicit)

• sType must be STRUCTURE_TYPE_PERF_HINT_INFO_QCOM

• pNext must be NULL

• type must be a valid PerfHintTypeQCOM value

See Also

VK_QCOM_queue_perf_hint, PerfHintTypeQCOM, StructureType, queueSetPerfHintQCOM

VkPhysicalDeviceQueuePerfHintFeaturesQCOM - Structure describing queue perf hint features that can be supported by an implementation

Members

This structure describes the following features:

Description

If the PhysicalDeviceQueuePerfHintFeaturesQCOM structure is included in the pNext chain of the PhysicalDeviceFeatures2 structure passed to getPhysicalDeviceFeatures2, it is filled in to indicate whether each corresponding feature is supported. If the application wishes to use a Device with any features described by PhysicalDeviceQueuePerfHintFeaturesQCOM, it must add an instance of the structure, with the desired feature members set to TRUE, to the pNext chain of DeviceCreateInfo when creating the Device.

Structure Chaining

Extends the structures

• DeviceCreateInfo

• PhysicalDeviceFeatures2

See Also

VK_QCOM_queue_perf_hint, Bool32, StructureType

VkPhysicalDeviceQueuePerfHintPropertiesQCOM - Structure describing queue perf hint properties for a physical device

Members

The members of the PhysicalDeviceQueuePerfHintPropertiesQCOM structure describe the following:

Description

If the queuePerfHint feature is supported by physicalDevice, supportedQueues must return at least one supported queue type.

If the PhysicalDeviceQueuePerfHintPropertiesQCOM structure is included in the pNext chain of the PhysicalDeviceProperties2 structure passed to getPhysicalDeviceProperties2, it is filled in with each corresponding implementation-dependent property.

Structure Chaining

Extends the structure

• PhysicalDeviceProperties2

See Also

VK_QCOM_queue_perf_hint, QueueFlags, StructureType

VkPerfHintTypeQCOM - Specifies the performance hint type

Description

• PERF_HINT_TYPE_DEFAULT_QCOM resets the performance hint state back to default for the queue.

• PERF_HINT_TYPE_FREQUENCY_MIN_QCOM specifies the queue should prioritize power and sets the frequency constraints fmin and fmax to Fmin.

• PERF_HINT_TYPE_FREQUENCY_MAX_QCOM specifies the queue should prioritize performance and sets the frequency constraints fmin and fmax to Fmax.

• PERF_HINT_TYPE_FREQUENCY_SCALED_QCOM specifies the queue should be balanced between performance and power and sets the frequency constraint fmin by applying a scale factor to Fmax. No constraint is applied to fmax.

See Also

VK_QCOM_queue_perf_hint, PerfHintInfoQCOM