vk_common_QueueWaitIdle() creates a syncobj, does a submit with no
batch buffers what translates to execute trivial_batch_bo and then
waits for syncobj to be signaled when trivial_batch_bo finishes.
On Xe KMD on other hand we can avoid the trivial_batch_bo submission
and instead use the special DRM_IOCTL_XE_EXEC with num_batch_buffer == 0
to get a syncobj to be signaled when the last exec finish execution.
This should free a bit GPU to execute more important workloads.
This will also optimize vkDeviceWaitIdle() that calls QueueWaitIdle().
It have to fallback to vk_common_QueueWaitIdle() when queue is in
VK_QUEUE_SUBMIT_MODE_THREADED mode because vkQueueWaitIdle()
could return but there still stuff in VK/CPU submission queue.
Also it could cause use after free when resources attached to
submission are freed before it is processed, example:
vkCreateFence() or vkCreateSemaphore()
vkQueueSubmit() // with Fence or Semaphore created above
vkQueueWaitIdle() // with the race it returns
vkDestroyFence() or vkDestroySemaphore()
// vk_queue_submit_thread_func() start to process submission above...
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30958>
Xe engine is not equal to hardware engine, it is just a submission
queue that will be scheduled in the hardware engine during process
time slice of the GPU.
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22058>
