Break down end-to-end scroll update latency UMA metrics

content/browser/renderer_host/render_widget_host_latency_tracker.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/render_widget_host_latency_tracker.h"
 
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 
@@ skipping 153 matching lines @@
   // This UMA metric tracks the time from when the original touch event is
   // created (averaged if there are multiple) to when the scroll gesture
   // results in final frame swap.
   for (size_t i = 0; i < original_component.event_count; i++) {
     UMA_HISTOGRAM_CUSTOM_COUNTS(
         "Event.Latency.TouchToScrollUpdateSwap",
         (swap_component.event_time - original_component.event_time)
             .InMicroseconds(),
         1, 1000000, 100);
   }
+
+  typedef std::pair<LatencyInfo::LatencyComponent, bool> ComponentPair;
+
+  ComponentPair rendering_scheduled_main_component;
+  ComponentPair rendering_scheduled_impl_component;
+  ComponentPair renderer_swap_component;

[jdduke (slow), 2015/02/11 23:22:02]

Do these always go together? If not, can we early out? If so, should we be
validating that?

[Yufeng Shen (Slow to review), 2015/02/12 02:59:02]

CHECK seems too restrict here. I will just do early return.

+  ComponentPair browser_received_swap_component;
+  ComponentPair gpu_swap_component;
+
+  rendering_scheduled_main_component.second =
+      latency.FindLatency(
+          ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_MAIN_COMPONENT,
+          0, &(rendering_scheduled_main_component.first));
+
+  rendering_scheduled_impl_component.second =
+      latency.FindLatency(
+          ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_IMPL_COMPONENT,
+          0, &(rendering_scheduled_impl_component.first));
+
+  renderer_swap_component.second =
+      latency.FindLatency(ui::INPUT_EVENT_LATENCY_RENDERER_SWAP_COMPONENT,
+                          0, &(renderer_swap_component.first));
+
+  browser_received_swap_component.second =
+      latency.FindLatency(
+          ui::INPUT_EVENT_BROWSER_RECEIVED_RENDERER_SWAP_COMPONENT,
+          0, &(browser_received_swap_component.first));
+
+  gpu_swap_component.second =
+      latency.FindLatency(ui::INPUT_EVENT_GPU_SWAP_BUFFER_COMPONENT,
+                          0, &(gpu_swap_component.first));
+
+  if (rendering_scheduled_main_component.second) {
+      UMA_HISTOGRAM_CUSTOM_COUNTS(
+          "Event.Latency.ScrollUpdateTouchToHandledMain",
+          (rendering_scheduled_main_component.first.event_time -
+           original_component.event_time).InMicroseconds(),
+          1, 1000000, 100);
+  }
+
+  if (rendering_scheduled_impl_component.second) {
+      UMA_HISTOGRAM_CUSTOM_COUNTS(
+          "Event.Latency.ScrollUpdateTouchToHandledImpl",
+          (rendering_scheduled_impl_component.first.event_time -
+           original_component.event_time).InMicroseconds(),
+          1, 1000000, 100);
+  }
+
+  if (renderer_swap_component.second) {
+    if (rendering_scheduled_main_component.second) {
+      UMA_HISTOGRAM_CUSTOM_COUNTS(
+          "Event.Latency.ScrollUpdateHandledMainToRendererSwap",
+          (renderer_swap_component.first.event_time -
+           rendering_scheduled_main_component.first.event_time).
+          InMicroseconds(),
+          1, 1000000, 100);
+    }
+
+    if (rendering_scheduled_impl_component.second) {
+      UMA_HISTOGRAM_CUSTOM_COUNTS(
+          "Event.Latency.ScrollUpdateHandledImplToRendererSwap",
+          (renderer_swap_component.first.event_time -
+           rendering_scheduled_impl_component.first.event_time).
+          InMicroseconds(),
+          1, 1000000, 100);
+    }
+
+    if (browser_received_swap_component.second) {
+      UMA_HISTOGRAM_CUSTOM_COUNTS(
+          "Event.Latency.ScrollUpdateRendererSwapToBrowserNotified",
+          (browser_received_swap_component.first.event_time -
+           renderer_swap_component.first.event_time).InMicroseconds(),
+          1, 1000000, 100);
+    }
+  }
+
+  if (gpu_swap_component.second) {
+    if (browser_received_swap_component.second) {
+      UMA_HISTOGRAM_CUSTOM_COUNTS(
+          "Event.Latency.ScrollUpdateBrowserNotifiedToBeforeGpuSwap",
+          (gpu_swap_component.first.event_time -
+           browser_received_swap_component.first.event_time).InMicroseconds(),
+          1, 1000000, 100);
+    }
+
+    UMA_HISTOGRAM_CUSTOM_COUNTS(
+        "Event.Latency.ScrollUpdateGpuSwap",
+        (swap_component.event_time -
+         gpu_swap_component.first.event_time).InMicroseconds(),
+        1, 1000000, 100);
+  }
 }
 
 // LatencyComponents generated in the renderer must have component IDs
 // provided to them by the browser process. This function adds the correct
 // component ID where necessary.
 void AddLatencyInfoComponentIds(LatencyInfo* latency,
                                 int64 latency_component_id) {
   LatencyInfo::LatencyMap new_components;
   auto lc = latency->latency_components.begin();
   while (lc != latency->latency_components.end()) {
@@ skipping 73 matching lines @@
   }
 }
 
 void RenderWidgetHostLatencyTracker::OnInputEventAck(
     const blink::WebInputEvent& event,
     LatencyInfo* latency) {
   DCHECK(latency);
 
   // Latency ends when it is acked but does not cause render scheduling.
   bool rendering_scheduled = latency->FindLatency(
-      ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_COMPONENT, 0, NULL);
+      ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_MAIN_COMPONENT, 0, nullptr);
+  rendering_scheduled |= latency->FindLatency(
+      ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_IMPL_COMPONENT, 0, nullptr);
 
   if (WebInputEvent::isGestureEventType(event.type)) {
     if (!rendering_scheduled) {
       latency->AddLatencyNumber(
           ui::INPUT_EVENT_LATENCY_TERMINATED_GESTURE_COMPONENT, 0, 0);
       // TODO(jdduke): Consider exposing histograms for gesture event types.
     }
     return;
   }
 
@@ skipping 83 matching lines @@
   // cause regressions.
   return std::max(
       browser_composite_latency_history_.Percentile(
           kBrowserCompositeLatencyEstimationPercentile) *
           kBrowserCompositeLatencyEstimationSlack,
       base::TimeDelta::FromMicroseconds(
           (1.0f * base::Time::kMicrosecondsPerSecond) / (3.0f * 60)));
 }
 
 }  // namespace content