Cleanup, better document some areas

1 files changed, 28 insertions, 39 deletions

diff --git a/src/device_context.cc b/src/device_context.cc
index 2214b71..b149311 100644
--- a/src/device_context.cc
+++ b/src/device_context.cc
@@ -1,7 +1,6 @@
 #include "device_context.hh"
 #include "queue_context.hh"
 
-#include <iostream>
 #include <utility>
 #include <vulkan/vulkan_core.h>
 
@@ -23,22 +22,6 @@ DeviceContext::~DeviceContext() {
     }
 }
 
-void DeviceContext::notify_acquire(const VkSwapchainKHR& swapchain,
-                                   const std::uint32_t& image_index,
-                                   const VkSemaphore& signal_semaphore) {
-
-    /*
-    std::cerr << "notify acquire for swapchain: " << swapchain << " : "
-              << image_index << '\n';
-    std::cerr << "    signal semaphore: " << signal_semaphore << '\n';
-    */
-
-    const auto it = this->swapchain_signals.try_emplace(swapchain).first;
-
-    // Doesn't matter if it was already there, overwrite it.
-    it->second.insert_or_assign(image_index, signal_semaphore);
-}
-
 DeviceContext::Clock::Clock(const DeviceContext& context) : device(context) {
     this->calibrate();
 }
@@ -92,17 +75,14 @@ DeviceContext::Clock::ticks_to_time(const std::uint64_t& ticks) const {
     return time_point_t{delta};
 }
 
-const auto debug_log_time2 = [](auto& stream, const auto& diff) {
-    using namespace std::chrono;
-    const auto ms = duration_cast<milliseconds>(diff);
-    const auto us = duration_cast<microseconds>(diff - ms);
-    const auto ns = duration_cast<nanoseconds>(diff - ms - us);
-    stream << ms << " " << us << " " << ns << '\n';
-};
+void DeviceContext::notify_acquire(const VkSwapchainKHR& swapchain,
+                                   const std::uint32_t& image_index,
+                                   const VkSemaphore& signal_semaphore) {
+    const auto it = this->swapchain_signals.try_emplace(swapchain).first;
 
-const auto debug_log_time = [](const auto& diff) {
-    debug_log_time2(std::cerr, diff);
-};
+    // Doesn't matter if it was already there, overwrite it.
+    it->second.insert_or_assign(image_index, signal_semaphore);
+}
 
 void DeviceContext::sleep_in_input() {
     // Present hasn't happened yet, we don't know what queue to attack.
@@ -110,26 +90,35 @@ void DeviceContext::sleep_in_input() {
         return;
     }
 
-    const auto before = std::chrono::steady_clock::now();
+    const auto& frames = this->present_queue->in_flight_frames;
+    // No frame here means we're behind the GPU and do not need to delay.
+    // If anything we should speed up...
+    if (!std::size(frames)) {
+        return;
+    }
+
     // If we're here, that means that there might be an outstanding frame that's
     // sitting on our present_queue which hasn't yet completed, so we need to
     // stall until it's finished.
-    const auto& frames = this->present_queue->in_flight_frames;
-    if (std::size(frames)) {
-        frames.back().submissions.back()->end_handle->get_time_spinlock();
-    }
-    const auto after = std::chrono::steady_clock::now();
-    //debug_log_time(after - before);
-    
-    // FIXME this should take into account 'cpu_time', which we currently do not...
-    // idk if it matters.
+    const auto& last_frame = frames.back();
+    assert(std::size(last_frame.submissions));
+    const auto& last_frame_submission = frames.back().submissions.back();
+    last_frame_submission->end_handle->get_time_spinlock();
+
+    // From our sleep in present implementation, just spinning until
+    // the previous frame has completed did not work well. This was because
+    // there was a delay between presentation and when new work was given
+    // to the GPU. If we stalled the CPU without trying to account for this, we
+    // would get huge frame drops, loss of throughput, and the GPU would even
+    // clock down. So naturally I am concerned about this approach, but it seems
+    // to perform well so far in my own testing and is just beautifully elegant.
 }
 
 void DeviceContext::notify_antilag_update(const VkAntiLagDataAMD& data) {
     this->antilag_mode = data.mode;
-    this->antilag_fps = data.maxFPS;
+    this->antilag_fps = data.maxFPS; // TODO
 
-    // This might not be provided (probably just to set some settings).
+    // This might not be provided (probably just to set some settings?).
     if (!data.pPresentationInfo) {
         return;
     }