render/vulkan: add a command buffer pool

Before re-using a VkCommandBuffer, we need to wait for its
operations to complete. Right now we unconditionally wait for
rendering to complete in vulkan_end(), however we have plans to
fix this [1]. To fully avoid blocking, we need to handle multiple
command buffers in flight at the same time (e.g. for multi-output,
or for rendering followed by texture uploads).

Implement a pool of command buffers. When we need to render, we
pick a command buffer from the pool which has completed its
operations. If we don't find one, try to allocate a new command
buffer. If we don't have slots in the pool anymore, block like we
did before.

[1]: https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/3574

1 files changed, 13 insertions, 1 deletions

diff --git a/include/render/vulkan.h b/include/render/vulkan.h
index a22d224f..d0a2ad85 100644
--- a/include/render/vulkan.h
+++ b/include/render/vulkan.h
@@ -45,6 +45,7 @@ struct wlr_vk_device {
 	struct {
 		PFN_vkGetMemoryFdPropertiesKHR getMemoryFdPropertiesKHR;
 		PFN_vkWaitSemaphoresKHR waitSemaphoresKHR;
+		PFN_vkGetSemaphoreCounterValueKHR getSemaphoreCounterValueKHR;
 	} api;
 
 	uint32_t format_prop_count;
@@ -136,6 +137,14 @@ struct wlr_vk_render_buffer {
 	bool transitioned;
 };
 
+struct wlr_vk_command_buffer {
+	VkCommandBuffer vk;
+	bool recording;
+	uint64_t timeline_point;
+};
+
+#define VULKAN_COMMAND_BUFFERS_CAP 64
+
 // Vulkan wlr_renderer implementation on top of a wlr_vk_device.
 struct wlr_vk_renderer {
 	struct wlr_renderer wlr_renderer;
@@ -156,13 +165,13 @@ struct wlr_vk_renderer {
 	uint64_t timeline_point;
 
 	struct wlr_vk_render_buffer *current_render_buffer;
+	struct wlr_vk_command_buffer *current_command_buffer;
 
 	// current frame id. Used in wlr_vk_texture.last_used
 	// Increased every time a frame is ended for the renderer
 	uint32_t frame;
 	VkRect2D scissor; // needed for clearing
 
-	VkCommandBuffer cb;
 	VkPipeline bound_pipe;
 
 	uint32_t render_width;
@@ -181,6 +190,9 @@ struct wlr_vk_renderer {
 
 	struct wl_list render_buffers; // wlr_vk_render_buffer.link
 
+	// Pool of command buffers
+	struct wlr_vk_command_buffer command_buffers[VULKAN_COMMAND_BUFFERS_CAP];
+
 	struct {
 		VkCommandBuffer cb;
 		bool recording;