Enum vk_mem_erupt::MemoryUsage

pub enum MemoryUsage {
    Unknown,
    GpuOnly,
    CpuOnly,
    CpuToGpu,
    GpuToCpu,
    CpuCopy,
    GpuLazilyAllocated,
}

Intended usage of memory.

Variants

Unknown

No intended memory usage specified. Use other members of AllocationCreateInfo to specify your requirements.

GpuOnly

Memory will be used on device only, so fast access from the device is preferred. It usually means device-local GPU (video) memory. No need to be mappable on host. It is roughly equivalent of D3D12_HEAP_TYPE_DEFAULT.

Usage:

• Resources written and read by device, e.g. images used as attachments.
• Resources transferred from host once (immutable) or infrequently and read by device multiple times, e.g. textures to be sampled, vertex buffers, uniform (constant) buffers, and majority of other types of resources used on GPU.

Allocation may still end up in erupt::vk::MemoryPropertyFlags::HOST_VISIBLE memory on some implementations. In such case, you are free to map it. You can use AllocationCreateFlags::MAPPED with this usage type.

CpuOnly

Memory will be mappable on host. It usually means CPU (system) memory. Guarantees to be erupt::vk::MemoryPropertyFlags::HOST_VISIBLE and erupt::vk::MemoryPropertyFlags::HOST_COHERENT. CPU access is typically uncached. Writes may be write-combined. Resources created in this pool may still be accessible to the device, but access to them can be slow. It is roughly equivalent of D3D12_HEAP_TYPE_UPLOAD.

Usage: Staging copy of resources used as transfer source.

CpuToGpu

Memory that is both mappable on host (guarantees to be erupt::vk::MemoryPropertyFlags::HOST_VISIBLE) and preferably fast to access by GPU. CPU access is typically uncached. Writes may be write-combined.

Usage: Resources written frequently by host (dynamic), read by device. E.g. textures, vertex buffers, uniform buffers updated every frame or every draw call.

GpuToCpu

Memory mappable on host (guarantees to be erupt::vk::MemoryPropertFlags::HOST_VISIBLE) and cached. It is roughly equivalent of D3D12_HEAP_TYPE_READBACK.

Usage:

• Resources written by device, read by host - results of some computations, e.g. screen capture, average scene luminance for HDR tone mapping.
• Any resources read or accessed randomly on host, e.g. CPU-side copy of vertex buffer used as source of transfer, but also used for collision detection.

CpuCopy

CPU memory - memory that is preferably not DEVICE_LOCAL, but also not guaranteed to be HOST_VISIBLE.

Usage: Staging copy of resources moved from GPU memory to CPU memory as part of custom paging/residency mechanism, to be moved back to GPU memory when needed.

GpuLazilyAllocated

Lazily allocated GPU memory having VK_MEMORY_PROPERTY_LAZILY_ALLOCATED_BIT. Exists mostly on mobile platforms. Using it on desktop PC or other GPUs with no such memory type present will fail the allocation.

Usage: Memory for transient attachment images (color attachments, depth attachments etc.), created with VK_IMAGE_USAGE_TRANSIENT_ATTACHMENT_BIT.

Allocations with this usage are always created as dedicated - it implies #VMA_ALLOCATION_CREATE_DEDICATED_MEMORY_BIT.

Trait Implementations

impl Clone for MemoryUsage

fn clone(&self) -> MemoryUsage

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for MemoryUsage

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Hash for MemoryUsage

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given Hasher.

impl Ord for MemoryUsage

fn cmp(&self, other: &MemoryUsage) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

Restrict a value to a certain interval.

impl PartialEq<MemoryUsage> for MemoryUsage

fn eq(&self, other: &MemoryUsage) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialOrd<MemoryUsage> for MemoryUsage

fn partial_cmp(&self, other: &MemoryUsage) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl Copy for MemoryUsage

impl Eq for MemoryUsage

impl StructuralEq for MemoryUsage

impl StructuralPartialEq for MemoryUsage