# VkQueueFamilyProperties

The `VkQueueFamilyProperties`

structure is defined as:

```
typedef struct VkQueueFamilyProperties {
VkQueueFlags queueFlags;
uint32_t queueCount;
uint32_t timestampValidBits;
VkExtent3D minImageTransferGranularity;
} VkQueueFamilyProperties;
```

`queueFlags`

is a bitmask of VkQueueFlagBits indicating capabilities of the queues in this queue family.`queueCount`

is the unsigned integer count of queues in this queue family. Each queue family must support at least one queue.`timestampValidBits`

is the unsigned integer count of meaningful bits in the timestamps written via vkCmdWriteTimestamp2 or vkCmdWriteTimestamp. The valid range for the count is 36 to 64 bits, or a value of 0, indicating no support for timestamps. Bits outside the valid range are guaranteed to be zeros.`minImageTransferGranularity`

is the minimum granularity supported for image transfer operations on the queues in this queue family.

The value returned in `minImageTransferGranularity`

has a unit of
compressed texel blocks for images having a block-compressed format, and a
unit of texels otherwise.

Possible values of `minImageTransferGranularity`

are:

- (0,0,0) specifies that only whole mip levels must be transferred
using the image transfer operations on the corresponding queues.
In this case, the following restrictions apply to all offset and extent
parameters of image transfer operations:
- The
`x`

,`y`

, and`z`

members of a VkOffset3D parameter must always be zero. - The
`width`

,`height`

, and`depth`

members of a VkExtent3D parameter must always match the width, height, and depth of the image subresource corresponding to the parameter, respectively.

- The
- (A
_{x}, A_{y}, A_{z}) where A_{x}, A_{y}, and A_{z}are all integer powers of two. In this case the following restrictions apply to all image transfer operations:`x`

,`y`

, and`z`

of a VkOffset3D parameter must be integer multiples of A_{x}, A_{y}, and A_{z}, respectively.`width`

of a VkExtent3D parameter must be an integer multiple of A_{x}, or else`x`

+`width`

must equal the width of the image subresource corresponding to the parameter.`height`

of a VkExtent3D parameter must be an integer multiple of A_{y}, or else`y`

+`height`

must equal the height of the image subresource corresponding to the parameter.`depth`

of a VkExtent3D parameter must be an integer multiple of A_{z}, or else`z`

+`depth`

must equal the depth of the image subresource corresponding to the parameter.- If the format of the image corresponding to the parameters is one of the block-compressed formats then for the purposes of the above calculations the granularity must be scaled up by the compressed texel block dimensions.

Queues supporting graphics and/or compute operations must report
(1,1,1) in `minImageTransferGranularity`

, meaning that there are
no additional restrictions on the granularity of image transfer operations
for these queues.
Other queues supporting image transfer operations are only required to
support whole mip level transfers, thus `minImageTransferGranularity`

for queues belonging to such queue families may be (0,0,0).

The Device Memory section describes memory properties queried from the physical device.

For physical device feature queries see the Features chapter.