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/libs/gui/OccupancyTracker.cpp b/libs/gui/OccupancyTracker.cpp
new file mode 100644
index 0000000..9687aaf
--- /dev/null
+++ b/libs/gui/OccupancyTracker.cpp
@@ -0,0 +1,117 @@
+/*
+ * Copyright 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#undef LOG_TAG
+#define LOG_TAG "OccupancyTracker"
+
+#include <gui/OccupancyTracker.h>
+#include <binder/Parcel.h>
+#include <utils/String8.h>
+#include <utils/Trace.h>
+
+#include <inttypes.h>
+
+namespace android {
+
+status_t OccupancyTracker::Segment::writeToParcel(Parcel* parcel) const {
+ status_t result = parcel->writeInt64(totalTime);
+ if (result != OK) {
+ return result;
+ }
+ result = parcel->writeUint64(static_cast<uint64_t>(numFrames));
+ if (result != OK) {
+ return result;
+ }
+ result = parcel->writeFloat(occupancyAverage);
+ if (result != OK) {
+ return result;
+ }
+ return parcel->writeBool(usedThirdBuffer);
+}
+
+status_t OccupancyTracker::Segment::readFromParcel(const Parcel* parcel) {
+ status_t result = parcel->readInt64(&totalTime);
+ if (result != OK) {
+ return result;
+ }
+ uint64_t uintNumFrames = 0;
+ result = parcel->readUint64(&uintNumFrames);
+ if (result != OK) {
+ return result;
+ }
+ numFrames = static_cast<size_t>(uintNumFrames);
+ result = parcel->readFloat(&occupancyAverage);
+ if (result != OK) {
+ return result;
+ }
+ return parcel->readBool(&usedThirdBuffer);
+}
+
+void OccupancyTracker::registerOccupancyChange(size_t occupancy) {
+ ATRACE_CALL();
+ nsecs_t now = systemTime();
+ nsecs_t delta = now - mLastOccupancyChangeTime;
+ if (delta > NEW_SEGMENT_DELAY) {
+ recordPendingSegment();
+ } else {
+ mPendingSegment.totalTime += delta;
+ if (mPendingSegment.mOccupancyTimes.count(mLastOccupancy)) {
+ mPendingSegment.mOccupancyTimes[mLastOccupancy] += delta;
+ } else {
+ mPendingSegment.mOccupancyTimes[mLastOccupancy] = delta;
+ }
+ }
+ if (occupancy > mLastOccupancy) {
+ ++mPendingSegment.numFrames;
+ }
+ mLastOccupancyChangeTime = now;
+ mLastOccupancy = occupancy;
+}
+
+std::vector<OccupancyTracker::Segment> OccupancyTracker::getSegmentHistory(
+ bool forceFlush) {
+ if (forceFlush) {
+ recordPendingSegment();
+ }
+ std::vector<Segment> segments(mSegmentHistory.cbegin(),
+ mSegmentHistory.cend());
+ mSegmentHistory.clear();
+ return segments;
+}
+
+void OccupancyTracker::recordPendingSegment() {
+ // Only record longer segments to get a better measurement of actual double-
+ // vs. triple-buffered time
+ if (mPendingSegment.numFrames > LONG_SEGMENT_THRESHOLD) {
+ float occupancyAverage = 0.0f;
+ bool usedThirdBuffer = false;
+ for (const auto& timePair : mPendingSegment.mOccupancyTimes) {
+ size_t occupancy = timePair.first;
+ float timeRatio = static_cast<float>(timePair.second) /
+ mPendingSegment.totalTime;
+ occupancyAverage += timeRatio * occupancy;
+ usedThirdBuffer = usedThirdBuffer || (occupancy > 1);
+ }
+ mSegmentHistory.push_front({mPendingSegment.totalTime,
+ mPendingSegment.numFrames, occupancyAverage, usedThirdBuffer});
+ if (mSegmentHistory.size() > MAX_HISTORY_SIZE) {
+ mSegmentHistory.pop_back();
+ }
+ }
+ mPendingSegment.clear();
+}
+
+} // namespace android