SF: Clear layer history when inconclusive to frequent

layer transition

BUG: 265561529
Test: atest LayerHistoryTest
Benchmark shows improvement with the changes https://android-build.googleplex.com/builds/abtd/run/L82600000959656128

Change-Id: I152aa97f00592960411133de150990747ca8b31d

3 files changed, 100 insertions, 15 deletions

diff --git a/services/surfaceflinger/Scheduler/LayerInfo.cpp b/services/surfaceflinger/Scheduler/LayerInfo.cpp
index 5a90d5866e..bae3739501 100644
--- a/services/surfaceflinger/Scheduler/LayerInfo.cpp
+++ b/services/surfaceflinger/Scheduler/LayerInfo.cpp
@@ -78,17 +78,16 @@ bool LayerInfo::isFrameTimeValid(const FrameTimeData& frameTime) const {
                                           .count();
 }
 
-bool LayerInfo::isFrequent(nsecs_t now) const {
-    using fps_approx_ops::operator>=;
+LayerInfo::Frequent LayerInfo::isFrequent(nsecs_t now) const {
     // If we know nothing about this layer (e.g. after touch event),
     // we consider it as frequent as it might be the start of an animation.
     if (mFrameTimes.size() < kFrequentLayerWindowSize) {
-        return true;
+        return {/* isFrequent */ true, /* clearHistory */ false, /* isConclusive */ true};
     }
 
     // Non-active layers are also infrequent
     if (mLastUpdatedTime < getActiveLayerThreshold(now)) {
-        return false;
+        return {/* isFrequent */ false, /* clearHistory */ false, /* isConclusive */ true};
     }
 
     // We check whether we can classify this layer as frequent or infrequent:
@@ -111,12 +110,20 @@ bool LayerInfo::isFrequent(nsecs_t now) const {
     }
 
     if (isFrequent || isInfrequent) {
-        return isFrequent;
+        // If the layer was previously inconclusive, we clear
+        // the history as indeterminate layers changed to frequent,
+        // and we should not look at the stale data.
+        return {isFrequent, isFrequent && !mIsFrequencyConclusive, /* isConclusive */ true};
     }
 
     // If we can't determine whether the layer is frequent or not, we return
-    // the last known classification.
-    return !mLastRefreshRate.infrequent;
+    // the last known classification and mark the layer frequency as inconclusive.
+    isFrequent = !mLastRefreshRate.infrequent;
+
+    // If the layer was previously tagged as animating, we clear
+    // the history as it is likely the layer just changed its behavior,
+    // and we should not look at stale data.
+    return {isFrequent, isFrequent && mLastRefreshRate.animating, /* isConclusive */ false};
 }
 
 Fps LayerInfo::getFps(nsecs_t now) const {
@@ -273,19 +280,18 @@ LayerInfo::LayerVote LayerInfo::getRefreshRateVote(const RefreshRateSelector& se
         return {LayerHistory::LayerVoteType::Max, Fps()};
     }
 
-    if (!isFrequent(now)) {
+    const LayerInfo::Frequent frequent = isFrequent(now);
+    mIsFrequencyConclusive = frequent.isConclusive;
+    if (!frequent.isFrequent) {
         ATRACE_FORMAT_INSTANT("infrequent");
         ALOGV("%s is infrequent", mName.c_str());
         mLastRefreshRate.infrequent = true;
-        // Infrequent layers vote for mininal refresh rate for
+        // Infrequent layers vote for minimal refresh rate for
         // battery saving purposes and also to prevent b/135718869.
         return {LayerHistory::LayerVoteType::Min, Fps()};
     }
 
-    // If the layer was previously tagged as animating or infrequent, we clear
-    // the history as it is likely the layer just changed its behavior
-    // and we should not look at stale data
-    if (mLastRefreshRate.animating || mLastRefreshRate.infrequent) {
+    if (frequent.clearHistory) {
         clearHistory(now);
     }
 
diff --git a/services/surfaceflinger/Scheduler/LayerInfo.h b/services/surfaceflinger/Scheduler/LayerInfo.h
index a3523ac25e..c5a60573f5 100644
--- a/services/surfaceflinger/Scheduler/LayerInfo.h
+++ b/services/surfaceflinger/Scheduler/LayerInfo.h
@@ -181,6 +181,7 @@ public:
         mFrameTimeValidSince = std::chrono::time_point<std::chrono::steady_clock>(timePoint);
         mLastRefreshRate = {};
         mRefreshRateHistory.clear();
+        mIsFrequencyConclusive = true;
     }
 
     void clearHistory(nsecs_t now) {
@@ -251,7 +252,15 @@ private:
         static constexpr float MARGIN_CONSISTENT_FPS = 1.0;
     };
 
-    bool isFrequent(nsecs_t now) const;
+    // Represents whether we were able to determine either layer is frequent or infrequent
+    bool mIsFrequencyConclusive = true;
+    struct Frequent {
+        bool isFrequent;
+        bool clearHistory;
+        // Represents whether we were able to determine isFrequent conclusively
+        bool isConclusive;
+    };
+    Frequent isFrequent(nsecs_t now) const;
     bool isAnimating(nsecs_t now) const;
     bool hasEnoughDataForHeuristic() const;
     std::optional<Fps> calculateRefreshRateIfPossible(const RefreshRateSelector&, nsecs_t now);
diff --git a/services/surfaceflinger/tests/unittests/LayerHistoryTest.cpp b/services/surfaceflinger/tests/unittests/LayerHistoryTest.cpp
index b7672768b4..85d86a7acc 100644
--- a/services/surfaceflinger/tests/unittests/LayerHistoryTest.cpp
+++ b/services/surfaceflinger/tests/unittests/LayerHistoryTest.cpp
@@ -84,7 +84,7 @@ protected:
     auto frequentLayerCount(nsecs_t now) const NO_THREAD_SAFETY_ANALYSIS {
         const auto& infos = history().mActiveLayerInfos;
         return std::count_if(infos.begin(), infos.end(), [now](const auto& pair) {
-            return pair.second.second->isFrequent(now);
+            return pair.second.second->isFrequent(now).isFrequent;
         });
     }
 
@@ -95,6 +95,13 @@ protected:
         });
     }
 
+    auto clearLayerHistoryCount(nsecs_t now) const NO_THREAD_SAFETY_ANALYSIS {
+        const auto& infos = history().mActiveLayerInfos;
+        return std::count_if(infos.begin(), infos.end(), [now](const auto& pair) {
+            return pair.second.second->isFrequent(now).clearHistory;
+        });
+    }
+
     void setDefaultLayerVote(Layer* layer,
                              LayerHistory::LayerVoteType vote) NO_THREAD_SAFETY_ANALYSIS {
         auto [found, layerPair] = history().findLayer(layer->getSequence());
@@ -764,6 +771,7 @@ TEST_F(LayerHistoryTest, frequentLayerBecomingInfrequentAndBack) {
     time += std::chrono::nanoseconds(3s).count();
     history().record(layer->getSequence(), layer->getLayerProps(), time, time,
                      LayerHistory::LayerUpdateType::Buffer);
+    EXPECT_EQ(0, clearLayerHistoryCount(time));
     ASSERT_EQ(1, summarizeLayerHistory(time).size());
     EXPECT_EQ(LayerHistory::LayerVoteType::Heuristic, summarizeLayerHistory(time)[0].vote);
     EXPECT_EQ(60_Hz, summarizeLayerHistory(time)[0].desiredRefreshRate);
@@ -778,6 +786,7 @@ TEST_F(LayerHistoryTest, frequentLayerBecomingInfrequentAndBack) {
     time += (MAX_FREQUENT_LAYER_PERIOD_NS + 1ms).count();
     history().record(layer->getSequence(), layer->getLayerProps(), time, time,
                      LayerHistory::LayerUpdateType::Buffer);
+    EXPECT_EQ(0, clearLayerHistoryCount(time));
     ASSERT_EQ(1, summarizeLayerHistory(time).size());
     EXPECT_EQ(LayerHistory::LayerVoteType::Min, summarizeLayerHistory(time)[0].vote);
     EXPECT_EQ(1, activeLayerCount());
@@ -787,6 +796,7 @@ TEST_F(LayerHistoryTest, frequentLayerBecomingInfrequentAndBack) {
     // posting another buffer should keep the layer infrequent
     history().record(layer->getSequence(), layer->getLayerProps(), time, time,
                      LayerHistory::LayerUpdateType::Buffer);
+    EXPECT_EQ(0, clearLayerHistoryCount(time));
     ASSERT_EQ(1, summarizeLayerHistory(time).size());
     EXPECT_EQ(LayerHistory::LayerVoteType::Min, summarizeLayerHistory(time)[0].vote);
     EXPECT_EQ(1, activeLayerCount());
@@ -798,6 +808,7 @@ TEST_F(LayerHistoryTest, frequentLayerBecomingInfrequentAndBack) {
                      LayerHistory::LayerUpdateType::Buffer);
     history().record(layer->getSequence(), layer->getLayerProps(), time, time,
                      LayerHistory::LayerUpdateType::Buffer);
+    EXPECT_EQ(1, clearLayerHistoryCount(time));
     ASSERT_EQ(1, summarizeLayerHistory(time).size());
     EXPECT_EQ(LayerHistory::LayerVoteType::Max, summarizeLayerHistory(time)[0].vote);
     EXPECT_EQ(1, activeLayerCount());
@@ -808,6 +819,7 @@ TEST_F(LayerHistoryTest, frequentLayerBecomingInfrequentAndBack) {
     time += std::chrono::nanoseconds(3s).count();
     history().record(layer->getSequence(), layer->getLayerProps(), time, time,
                      LayerHistory::LayerUpdateType::Buffer);
+    EXPECT_EQ(0, clearLayerHistoryCount(time));
     ASSERT_EQ(1, summarizeLayerHistory(time).size());
     EXPECT_EQ(LayerHistory::LayerVoteType::Max, summarizeLayerHistory(time)[0].vote);
     EXPECT_EQ(1, activeLayerCount());
@@ -818,6 +830,64 @@ TEST_F(LayerHistoryTest, frequentLayerBecomingInfrequentAndBack) {
     time += (60_Hz).getPeriodNsecs();
     history().record(layer->getSequence(), layer->getLayerProps(), time, time,
                      LayerHistory::LayerUpdateType::Buffer);
+    EXPECT_EQ(0, clearLayerHistoryCount(time));
+    ASSERT_EQ(1, summarizeLayerHistory(time).size());
+    EXPECT_EQ(LayerHistory::LayerVoteType::Max, summarizeLayerHistory(time)[0].vote);
+    EXPECT_EQ(1, activeLayerCount());
+    EXPECT_EQ(1, frequentLayerCount(time));
+    EXPECT_EQ(0, animatingLayerCount(time));
+}
+
+TEST_F(LayerHistoryTest, inconclusiveLayerBecomingFrequent) {
+    auto layer = createLayer();
+
+    EXPECT_CALL(*layer, isVisible()).WillRepeatedly(Return(true));
+    EXPECT_CALL(*layer, getFrameRateForLayerTree()).WillRepeatedly(Return(Layer::FrameRate()));
+
+    nsecs_t time = systemTime();
+
+    EXPECT_EQ(1, layerCount());
+    EXPECT_EQ(0, activeLayerCount());
+    EXPECT_EQ(0, frequentLayerCount(time));
+    EXPECT_EQ(0, animatingLayerCount(time));
+
+    // Fill up the window with frequent updates
+    for (int i = 0; i < FREQUENT_LAYER_WINDOW_SIZE; i++) {
+        history().record(layer->getSequence(), layer->getLayerProps(), time, time,
+                         LayerHistory::LayerUpdateType::Buffer);
+        time += (60_Hz).getPeriodNsecs();
+
+        EXPECT_EQ(1, layerCount());
+        ASSERT_EQ(1, summarizeLayerHistory(time).size());
+        EXPECT_EQ(LayerHistory::LayerVoteType::Max, summarizeLayerHistory(time)[0].vote);
+        EXPECT_EQ(1, activeLayerCount());
+        EXPECT_EQ(1, frequentLayerCount(time));
+    }
+
+    // posting infrequent buffers after long inactivity should make the layer
+    // inconclusive but frequent.
+    time += std::chrono::nanoseconds(3s).count();
+    history().record(layer->getSequence(), layer->getLayerProps(), time, time,
+                     LayerHistory::LayerUpdateType::Buffer);
+    time += (MAX_FREQUENT_LAYER_PERIOD_NS + 1ms).count();
+    history().record(layer->getSequence(), layer->getLayerProps(), time, time,
+                     LayerHistory::LayerUpdateType::Buffer);
+    EXPECT_EQ(0, clearLayerHistoryCount(time));
+    ASSERT_EQ(1, summarizeLayerHistory(time).size());
+    EXPECT_EQ(LayerHistory::LayerVoteType::Heuristic, summarizeLayerHistory(time)[0].vote);
+    EXPECT_EQ(1, activeLayerCount());
+    EXPECT_EQ(1, frequentLayerCount(time));
+    EXPECT_EQ(0, animatingLayerCount(time));
+
+    // posting more buffers should make the layer frequent and switch the refresh rate to max
+    // by clearing the history
+    history().record(layer->getSequence(), layer->getLayerProps(), time, time,
+                     LayerHistory::LayerUpdateType::Buffer);
+    history().record(layer->getSequence(), layer->getLayerProps(), time, time,
+                     LayerHistory::LayerUpdateType::Buffer);
+    history().record(layer->getSequence(), layer->getLayerProps(), time, time,
+                     LayerHistory::LayerUpdateType::Buffer);
+    EXPECT_EQ(1, clearLayerHistoryCount(time));
     ASSERT_EQ(1, summarizeLayerHistory(time).size());
     EXPECT_EQ(LayerHistory::LayerVoteType::Max, summarizeLayerHistory(time)[0].vote);
     EXPECT_EQ(1, activeLayerCount());