Recover from buffer stuffing for canned animations
Buffer stuffing occurs when SurfaceFlinger misses a frame, but the
client continues to produce buffers at the same rate, causing a
greater risk for jank to occur. Recovery is achieved for canned
animations by adjusting the animation timeline on the client side so
that SurfaceFlinger is no longer behind.
Use SF backdoor command 1045 to inject jank.
Usage: adb shell service call SurfaceFlinger 1045 f 1
Bug: b/294922229
Test: atest EventThreadTest
Test: presubmit, manually check perfetto traces
Flag: android.view.flags.buffer_stuffing_recovery
Change-Id: I38f0eb3d6ef1331e07d6022fa3a0e16c556ba06f
diff --git a/services/surfaceflinger/Scheduler/EventThread.cpp b/services/surfaceflinger/Scheduler/EventThread.cpp
index e385f18..24d387a 100644
--- a/services/surfaceflinger/Scheduler/EventThread.cpp
+++ b/services/surfaceflinger/Scheduler/EventThread.cpp
@@ -44,10 +44,8 @@
#include <common/FlagManager.h>
#include <scheduler/VsyncConfig.h>
-#include "DisplayHardware/DisplayMode.h"
#include "FrameTimeline.h"
#include "VSyncDispatch.h"
-#include "VSyncTracker.h"
#include "EventThread.h"
@@ -472,6 +470,14 @@
mCondition.notify_all();
}
+// Merge lists of buffer stuffed Uids
+void EventThread::addBufferStuffedUids(BufferStuffingMap bufferStuffedUids) {
+ std::lock_guard<std::mutex> lock(mMutex);
+ for (auto& [uid, count] : bufferStuffedUids) {
+ mBufferStuffedUids.emplace_or_replace(uid, count);
+ }
+}
+
void EventThread::threadMain(std::unique_lock<std::mutex>& lock) {
DisplayEventConsumers consumers;
@@ -701,6 +707,10 @@
void EventThread::dispatchEvent(const DisplayEventReceiver::Event& event,
const DisplayEventConsumers& consumers) {
+ // List of Uids that have been sent vsync data with queued buffer count.
+ // Used to keep track of which Uids can be removed from the map of
+ // buffer stuffed clients.
+ ftl::SmallVector<uid_t, 10> uidsPostedQueuedBuffers;
for (const auto& consumer : consumers) {
DisplayEventReceiver::Event copy = event;
if (event.header.type == DisplayEventReceiver::DISPLAY_EVENT_VSYNC) {
@@ -710,6 +720,13 @@
event.vsync.vsyncData.preferredExpectedPresentationTime(),
event.vsync.vsyncData.preferredDeadlineTimestamp());
}
+ auto it = mBufferStuffedUids.find(consumer->mOwnerUid);
+ if (it != mBufferStuffedUids.end()) {
+ copy.vsync.vsyncData.numberQueuedBuffers = it->second;
+ uidsPostedQueuedBuffers.emplace_back(consumer->mOwnerUid);
+ } else {
+ copy.vsync.vsyncData.numberQueuedBuffers = 0;
+ }
switch (consumer->postEvent(copy)) {
case NO_ERROR:
break;
@@ -725,6 +742,12 @@
removeDisplayEventConnectionLocked(consumer);
}
}
+ // The clients that have already received the queued buffer count
+ // can be removed from the buffer stuffed Uid list to avoid
+ // being sent duplicate messages.
+ for (auto uid : uidsPostedQueuedBuffers) {
+ mBufferStuffedUids.erase(uid);
+ }
if (event.header.type == DisplayEventReceiver::DISPLAY_EVENT_VSYNC &&
FlagManager::getInstance().vrr_config()) {
mLastCommittedVsyncTime =
diff --git a/services/surfaceflinger/Scheduler/EventThread.h b/services/surfaceflinger/Scheduler/EventThread.h
index c3c7eb0..02e2592 100644
--- a/services/surfaceflinger/Scheduler/EventThread.h
+++ b/services/surfaceflinger/Scheduler/EventThread.h
@@ -32,7 +32,6 @@
#include <thread>
#include <vector>
-#include "DisplayHardware/DisplayMode.h"
#include "TracedOrdinal.h"
#include "VSyncDispatch.h"
#include "VsyncSchedule.h"
@@ -55,6 +54,7 @@
// ---------------------------------------------------------------------------
using FrameRateOverride = DisplayEventReceiver::Event::FrameRateOverride;
+using BufferStuffingMap = ftl::SmallMap<uid_t, uint32_t, 10>;
enum class VSyncRequest {
None = -2,
@@ -134,6 +134,10 @@
virtual void onHdcpLevelsChanged(PhysicalDisplayId displayId, int32_t connectedLevel,
int32_t maxLevel) = 0;
+
+ // An elevated number of queued buffers in the server is detected. This propagates a
+ // flag to Choreographer indicating that buffer stuffing recovery should begin.
+ virtual void addBufferStuffedUids(BufferStuffingMap bufferStuffedUids);
};
struct IEventThreadCallback {
@@ -184,6 +188,8 @@
void onHdcpLevelsChanged(PhysicalDisplayId displayId, int32_t connectedLevel,
int32_t maxLevel) override;
+ void addBufferStuffedUids(BufferStuffingMap bufferStuffedUids) override;
+
private:
friend EventThreadTest;
@@ -224,6 +230,10 @@
scheduler::VSyncCallbackRegistration mVsyncRegistration GUARDED_BY(mMutex);
frametimeline::TokenManager* const mTokenManager;
+ // All consumers that need to recover from buffer stuffing and the number
+ // of their queued buffers.
+ BufferStuffingMap mBufferStuffedUids GUARDED_BY(mMutex);
+
IEventThreadCallback& mCallback;
std::thread mThread;
diff --git a/services/surfaceflinger/Scheduler/Scheduler.cpp b/services/surfaceflinger/Scheduler/Scheduler.cpp
index b83ff19..b984e92 100644
--- a/services/surfaceflinger/Scheduler/Scheduler.cpp
+++ b/services/surfaceflinger/Scheduler/Scheduler.cpp
@@ -940,6 +940,11 @@
return mFrameRateOverrideMappings.updateFrameRateOverridesByContent(frameRateOverrides);
}
+void Scheduler::addBufferStuffedUids(BufferStuffingMap bufferStuffedUids) {
+ if (!mRenderEventThread) return;
+ mRenderEventThread->addBufferStuffedUids(std::move(bufferStuffedUids));
+}
+
void Scheduler::promotePacesetterDisplay(PhysicalDisplayId pacesetterId, PromotionParams params) {
std::shared_ptr<VsyncSchedule> pacesetterVsyncSchedule;
{
diff --git a/services/surfaceflinger/Scheduler/Scheduler.h b/services/surfaceflinger/Scheduler/Scheduler.h
index c88b563..1842426 100644
--- a/services/surfaceflinger/Scheduler/Scheduler.h
+++ b/services/surfaceflinger/Scheduler/Scheduler.h
@@ -42,7 +42,6 @@
#include <ui/DisplayId.h>
#include <ui/DisplayMap.h>
-#include "Display/DisplayModeRequest.h"
#include "EventThread.h"
#include "FrameRateOverrideMappings.h"
#include "ISchedulerCallback.h"
@@ -332,6 +331,10 @@
mPacesetterFrameDurationFractionToSkip = frameDurationFraction;
}
+ // Propagates a flag to the EventThread indicating that buffer stuffing
+ // recovery should begin.
+ void addBufferStuffedUids(BufferStuffingMap bufferStuffedUids);
+
private:
friend class TestableScheduler;