Track the last release fence per layer stack
Merging fences prior to calling CompositionEngine#present results in
occassional missed frames in Surfaceflinger. Merging fences here was
originally needed to relieve memory pressure. Instead, we can track
each layer stack's future release fence with a map between a layer
stack and its last fence, as it can be assumed that multiple fences
for the same layer stack can be be dropped.
Fixes: b/330841053
Test: SurfaceFlinger_test
Test: presubmit
Change-Id: I7ca3a226ff77bc31d93fdb4708c3e9089f423803
diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index cd2120e..edd9f9c 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -15,7 +15,7 @@
*/
// TODO(b/129481165): remove the #pragma below and fix conversion issues
-#include "TransactionCallbackInvoker.h"
+
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wconversion"
@@ -24,8 +24,6 @@
#define LOG_TAG "Layer"
#define ATRACE_TAG ATRACE_TAG_GRAPHICS
-#include "Layer.h"
-
#include <android-base/properties.h>
#include <android-base/stringprintf.h>
#include <binder/IPCThreadState.h>
@@ -74,10 +72,12 @@
#include "FrameTracer/FrameTracer.h"
#include "FrontEnd/LayerCreationArgs.h"
#include "FrontEnd/LayerHandle.h"
+#include "Layer.h"
#include "LayerProtoHelper.h"
#include "MutexUtils.h"
#include "SurfaceFlinger.h"
#include "TimeStats/TimeStats.h"
+#include "TransactionCallbackInvoker.h"
#include "TunnelModeEnabledReporter.h"
#include "Utils/FenceUtils.h"
@@ -2937,26 +2937,13 @@
ch->previousReleaseFences.emplace_back(std::move(futureFenceResult));
ch->name = mName;
} else {
- // If we didn't get a release callback yet, e.g. some scenarios when capturing
- // screenshots asynchronously, then make sure we don't drop the fence.
- mAdditionalPreviousReleaseFences.emplace_back(std::move(futureFenceResult));
- std::vector<ftl::Future<FenceResult>> mergedFences;
- sp<Fence> prevFence = nullptr;
- // For a layer that's frequently screenshotted, try to merge fences to make sure we
- // don't grow unbounded.
- for (auto& futureReleaseFence : mAdditionalPreviousReleaseFences) {
- auto result = futureReleaseFence.wait_for(0s);
- if (result != std::future_status::ready) {
- mergedFences.emplace_back(std::move(futureReleaseFence));
- continue;
- }
- mergeFence(getDebugName(), futureReleaseFence.get().value_or(Fence::NO_FENCE),
- prevFence);
- }
- if (prevFence != nullptr) {
- mergedFences.emplace_back(ftl::yield(FenceResult(std::move(prevFence))));
- }
- mAdditionalPreviousReleaseFences.swap(mergedFences);
+ // If we didn't get a release callback yet (e.g. some scenarios when capturing
+ // screenshots asynchronously) then make sure we don't drop the fence.
+ // Older fences for the same layer stack can be dropped when a new fence arrives.
+ // An assumption here is that RenderEngine performs work sequentially, so an
+ // incoming fence will not fire before an existing fence.
+ mAdditionalPreviousReleaseFences.emplace_or_replace(layerStack,
+ std::move(futureFenceResult));
}
if (mBufferInfo.mBuffer) {
@@ -3506,10 +3493,10 @@
handle->previousFrameNumber = mDrawingState.previousFrameNumber;
if (FlagManager::getInstance().ce_fence_promise() &&
mPreviousReleaseBufferEndpoint == handle->listener) {
- // Add fences from previous screenshots now so that they can be dispatched to the
+ // Add fence from previous screenshot now so that it can be dispatched to the
// client.
- for (auto& futureReleaseFence : mAdditionalPreviousReleaseFences) {
- handle->previousReleaseFences.emplace_back(std::move(futureReleaseFence));
+ for (auto& [_, future] : mAdditionalPreviousReleaseFences) {
+ handle->previousReleaseFences.emplace_back(std::move(future));
}
mAdditionalPreviousReleaseFences.clear();
} else if (FlagManager::getInstance().screenshot_fence_preservation() &&