[ET-VK] 6/n Split dispatches between multiple command buffers. Repurpose submit_current_cmd_and_wait to wait based on input flag.

This diff makes changes to the `submit_current_cmd_and_wait` function in the `ComputeGraph` class to repurpose it to wait for command buffer completion based on an input flag. The function is renamed to `submit_current_cmd` and now takes an additional `wait` parameter. If `wait` is `true`, the function submits the command buffer to the GPU and waits for its completion. Otherwise, it only submits the command buffer without waiting.

Differential Revision: [D78360042](https://our.internmc.facebook.com/intern/diff/D78360042/)

ghstack-source-id: 296443189
Pull Request resolved: #12529

Author: trivedivivek

backends/vulkan/runtime/graph/ComputeGraph.cpp

@@ -759,11 +759,16 @@ void ComputeGraph::prepare_pipelines() {
       vkapi::ComputePipelineCache::Hasher>();
 }
 
-void ComputeGraph::submit_current_cmd_and_wait(const bool final_use) {
-  vkapi::VulkanFence fence = context_->fences().get_fence();
-  context_->submit_cmd_to_gpu(fence.get_submit_handle(), final_use);
-  fence.wait();
-  context_->fences().return_fence(fence);
+void ComputeGraph::submit_current_cmd(const bool final_use, bool wait) {
+  if (wait) {
+    // Submit and wait for command buffer
+    vkapi::VulkanFence fence = context_->fences().get_fence();
+    context_->submit_cmd_to_gpu(fence.get_submit_handle(), final_use);
+    fence.wait();
+    context_->fences().return_fence(fence);
+  } else {
+    context_->submit_cmd_to_gpu(VK_NULL_HANDLE, final_use);
+  }
 }
 
 void ComputeGraph::encode_prepack() {
@@ -772,13 +777,9 @@ void ComputeGraph::encode_prepack() {
   }
 }
 
-void ComputeGraph::prepack() const {
+void ComputeGraph::prepack() {
   // Submit and execute the command buffer
-  vkapi::VulkanFence fence = context_->fences().get_fence();
-  context_->submit_cmd_to_gpu(fence.get_submit_handle(), /*final_use = */ true);
-  fence.wait();
-  context_->fences().return_fence(fence);
-
+  submit_current_cmd(/*final_use = */ true, /*wait = */ true);
   context_->flush();
 }
 
@@ -791,7 +792,7 @@ void ComputeGraph::run_prepack() {
     size_t threshold = submitted ? config_.prepack_threshold_nbytes
                                  : config_.prepack_initial_threshold_nbytes;
     if (not_terminal && staging_nbytes_in_cmd_ > threshold) {
-      submit_current_cmd_and_wait(/*final_use=*/true);
+      submit_current_cmd(/*final_use=*/true, /*wait=*/true);
       context_->flush();
       staging_nbytes_in_cmd_ = 0;
       context_->set_cmd();
@@ -801,7 +802,7 @@ void ComputeGraph::run_prepack() {
     node->encode(this);
     i++;
   }
-  submit_current_cmd_and_wait(/*final_use=*/true);
+  submit_current_cmd(/*final_use=*/true, /*wait=*/true);
   context_->flush();
   staging_nbytes_in_cmd_ = 0;
 }
@@ -823,7 +824,7 @@ void ComputeGraph::encode_execute() {
 
 void ComputeGraph::execute() {
   if (execute_pending_first_submission) {
-    submit_current_cmd_and_wait(/*final_use=*/false);
+    submit_current_cmd(/*final_use=*/false, /*wait=*/true);
     execute_pending_first_submission = false;
   } else {
     vkapi::VulkanFence fence = context_->fences().get_fence();

backends/vulkan/runtime/graph/ComputeGraph.h

@@ -825,9 +825,9 @@ class ComputeGraph final {
 
   /*
    * Submits the current command buffer in the Context to the GPU for execution,
-   * and wait for it to complete before returning.
+   * and wait for it to complete before returning, if wait is True.
    */
-  void submit_current_cmd_and_wait(const bool final_use = false);
+  void submit_current_cmd(const bool final_use = false, bool wait = true);
 
  public:
   //
@@ -839,7 +839,7 @@ class ComputeGraph final {
   }
 
   void encode_prepack();
-  void prepack() const;
+  void prepack();
 
   /*
    * Executes prepacking operations to transfer model weight data from the CPU