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|  | 18 | + | 
|  | 19 | +## Components | 
|  | 20 | + | 
|  | 21 | +### VulkanDeviceAPI | 
|  | 22 | + | 
|  | 23 | +Implements the TVM DeviceAPI interface. Owns the core Vulkan datastructures. Is | 
|  | 24 | +responsible for initializing the Vulkan instance and devices, querying for | 
|  | 25 | +possible extensions. | 
|  | 26 | + | 
|  | 27 | +### VulkanThreadEntry | 
|  | 28 | + | 
|  | 29 | +Thread-local state for the Vulkan runtime. Maintains a staging buffer (for | 
|  | 30 | +copies), and a VulkanStream per device. | 
|  | 31 | + | 
|  | 32 | +### VulkanWrappedFunc | 
|  | 33 | + | 
|  | 34 | +Responsible for launching computation kernels. Responsible for obtaining a | 
|  | 35 | +VulkanPipeline instance (from the VulkanModuleNode), and launches the kernel | 
|  | 36 | +(via immediate or deferred mode) on the active VulkanStream instance. | 
|  | 37 | + | 
|  | 38 | +## Stream execution in the Vulkan programming model. | 
|  | 39 | + | 
|  | 40 | +The natural model for TVM DeviceAPI implementation and runtime follows the CUDA | 
|  | 41 | +API model. That is, we launch "kernels" onto a (implicit or explicit) "stream" | 
|  | 42 | +(which execute asynchronously with respect to the host, but ordered with respect | 
|  | 43 | +to the stream), and explicitly synchronize the stream with respect to the host. | 
|  | 44 | +We simulate this behaviour in the Vulkan model by maintaining a thread-local | 
|  | 45 | +`vkCommandBuffer` instance, and queueing up (or eagerly executing, depending on | 
|  | 46 | +the availability of the `VK_KHR_push_descriptor` extension). When we synchronize | 
|  | 47 | +the stream, we end the command buffer recording, submit it to the device queue, | 
|  | 48 | +and wait on the corresponding fence. | 
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