Memory management is an important part of Vulkan. The VK_EXT_memory_budget extension was designed to allow some implementations to advertise even more fine grained details about the device memory heaps.
There are two important concepts this extension tries to help with
- For example, a device memory heap might expose it supports
2GB, but after 1.5GB has been allocated the platform may try to reclaim memory - potentially resulting in allocations migrating to slower memory, OOM conditions, or even process termination. - Another process on the machine might also be attempting to use the device memory as well.
VkPhysicalDeviceMemoryBudgetPropertiesEXT::heapBudget presents how much memory the current process can use before possible allocation failure or performance degradation.
VkPhysicalDeviceMemoryBudgetPropertiesEXT::heapUsage will display the current process estimated heap usage.
With this information, the idea is for an application at some interval (once per frame, per few seconds, etc) to query heapBudget and heapUsage. From here the application can notice if they are over budget and decide how it wants to handle the memory situation (free it, move to host memory, changing mipmap levels, etc). A suggestion is to look at VK_EXT_memory_priority too as it was designed to help with this part of memory management.