[hud] Implement GPU load display as a HUD item

src/dxvk/hud/dxvk_hud.cpp

@@ -43,6 +43,7 @@ namespace dxvk::hud {
     addItem<HudDrawCallStatsItem>("drawcalls", device);
     addItem<HudPipelineStatsItem>("pipelines", device);
     addItem<HudMemoryStatsItem>("memory", device);
+    addItem<HudGpuLoadItem>("gpuload", device);
   }
   
   

src/dxvk/hud/dxvk_hud_item.cpp

@@ -431,4 +431,50 @@ namespace dxvk::hud {
     return position;
   }
 
+
+  HudGpuLoadItem::HudGpuLoadItem(const Rc<DxvkDevice>& device)
+  : m_device(device) {
+
+  }
+
+
+  HudGpuLoadItem::~HudGpuLoadItem() {
+
+  }
+
+
+  void HudGpuLoadItem::update(dxvk::high_resolution_clock::time_point time) {
+    uint64_t ticks = std::chrono::duration_cast<std::chrono::microseconds>(time - m_lastUpdate).count();
+
+    if (ticks >= UpdateInterval) {
+      DxvkStatCounters counters = m_device->getStatCounters();
+      uint64_t currGpuIdleTicks = counters.getCtr(DxvkStatCounter::GpuIdleTicks);
+
+      m_diffGpuIdleTicks = currGpuIdleTicks - m_prevGpuIdleTicks;
+      m_prevGpuIdleTicks = currGpuIdleTicks;
+
+      uint64_t busyTicks = ticks > m_diffGpuIdleTicks
+        ? uint64_t(ticks - m_diffGpuIdleTicks)
+        : uint64_t(0);
+
+      m_gpuLoadString = str::format("GPU: ", (100 * busyTicks) / ticks, "%");
+      m_lastUpdate = time;
+    }
+  }
+
+
+  HudPos HudGpuLoadItem::render(
+          HudRenderer&      renderer,
+          HudPos            position) {
+    position.y += 16.0f;
+
+    renderer.drawText(16.0f,
+      { position.x, position.y },
+      { 1.0f, 1.0f, 1.0f, 1.0f },
+      m_gpuLoadString);
+
+    position.y += 8.0f;
+    return position;
+  }
+
 }

src/dxvk/hud/dxvk_hud_item.h

@@ -322,4 +322,36 @@ namespace dxvk::hud {
 
   };
 
+
+  /**
+   * \brief HUD item to display GPU load
+   */
+  class HudGpuLoadItem : public HudItem {
+    constexpr static int64_t UpdateInterval = 500'000;
+  public:
+
+    HudGpuLoadItem(const Rc<DxvkDevice>& device);
+
+    ~HudGpuLoadItem();
+
+    void update(dxvk::high_resolution_clock::time_point time);
+
+    HudPos render(
+            HudRenderer&      renderer,
+            HudPos            position);
+
+  private:
+
+    Rc<DxvkDevice> m_device;
+
+    uint64_t m_prevGpuIdleTicks = 0;
+    uint64_t m_diffGpuIdleTicks = 0;
+
+    std::string m_gpuLoadString = "GPU: ";
+
+    dxvk::high_resolution_clock::time_point m_lastUpdate
+      = dxvk::high_resolution_clock::now();
+
+  };
+
 }