BufferQueue/SF: Add OccupancyTracker
Adds an OccupancyTracker to BufferQueue. This module keeps track of
how many buffers are in the queue over time, which, in combination
with various aggregation of these statistics, allows SurfaceFlinger
to report what fraction of the time a given layer was double- or
triple-buffered.
Change-Id: Ida6e967dc5483c00a633e9fe03998e420dd88502
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 91815f3..a730ac6 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -1049,7 +1049,11 @@
const LayerVector& layers(mDrawingState.layersSortedByZ);
const size_t count = layers.size();
for (size_t i=0 ; i<count ; i++) {
- layers[i]->onPostComposition();
+ bool frameLatched = layers[i]->onPostComposition();
+ if (frameLatched) {
+ recordBufferingStats(layers[i]->getName().string(),
+ layers[i]->getOccupancyHistory(false));
+ }
}
sp<Fence> presentFence = mHwc->getRetireFence(HWC_DISPLAY_PRIMARY);
@@ -1641,6 +1645,8 @@
if (!mLayersPendingRemoval.isEmpty()) {
// Notify removed layers now that they can't be drawn from
for (size_t i = 0; i < mLayersPendingRemoval.size(); i++) {
+ recordBufferingStats(mLayersPendingRemoval[i]->getName().string(),
+ mLayersPendingRemoval[i]->getOccupancyHistory(true));
mLayersPendingRemoval[i]->onRemoved();
}
mLayersPendingRemoval.clear();
@@ -2720,6 +2726,59 @@
NUM_BUCKETS - 1, bucketTimeSec, percent);
}
+void SurfaceFlinger::recordBufferingStats(const char* layerName,
+ std::vector<OccupancyTracker::Segment>&& history) {
+ Mutex::Autolock lock(mBufferingStatsMutex);
+ auto& stats = mBufferingStats[layerName];
+ for (const auto& segment : history) {
+ if (!segment.usedThirdBuffer) {
+ stats.twoBufferTime += segment.totalTime;
+ }
+ if (segment.occupancyAverage < 1.0f) {
+ stats.doubleBufferedTime += segment.totalTime;
+ } else if (segment.occupancyAverage < 2.0f) {
+ stats.tripleBufferedTime += segment.totalTime;
+ }
+ ++stats.numSegments;
+ stats.totalTime += segment.totalTime;
+ }
+}
+
+void SurfaceFlinger::dumpBufferingStats(String8& result) const {
+ result.append("Buffering stats:\n");
+ result.append(" [Layer name] <Active time> <Two buffer> "
+ "<Double buffered> <Triple buffered>\n");
+ Mutex::Autolock lock(mBufferingStatsMutex);
+ typedef std::tuple<std::string, float, float, float> BufferTuple;
+ std::map<float, BufferTuple, std::greater<float>> sorted;
+ for (const auto& statsPair : mBufferingStats) {
+ const char* name = statsPair.first.c_str();
+ const BufferingStats& stats = statsPair.second;
+ if (stats.numSegments == 0) {
+ continue;
+ }
+ float activeTime = ns2ms(stats.totalTime) / 1000.0f;
+ float twoBufferRatio = static_cast<float>(stats.twoBufferTime) /
+ stats.totalTime;
+ float doubleBufferRatio = static_cast<float>(
+ stats.doubleBufferedTime) / stats.totalTime;
+ float tripleBufferRatio = static_cast<float>(
+ stats.tripleBufferedTime) / stats.totalTime;
+ sorted.insert({activeTime, {name, twoBufferRatio,
+ doubleBufferRatio, tripleBufferRatio}});
+ }
+ for (const auto& sortedPair : sorted) {
+ float activeTime = sortedPair.first;
+ const BufferTuple& values = sortedPair.second;
+ result.appendFormat(" [%s] %.2f %.3f %.3f %.3f\n",
+ std::get<0>(values).c_str(), activeTime,
+ std::get<1>(values), std::get<2>(values),
+ std::get<3>(values));
+ }
+ result.append("\n");
+}
+
+
void SurfaceFlinger::dumpAllLocked(const Vector<String16>& args, size_t& index,
String8& result) const
{
@@ -2773,6 +2832,8 @@
dumpStaticScreenStats(result);
result.append("\n");
+ dumpBufferingStats(result);
+
/*
* Dump the visible layer list
*/