SurfaceFlinger: Trace pending BufferStateLayer buffers.
In BufferQueueLayer the BufferQueueConsumer lives inside the server
process, and ATRACE's an integer indicating the current number of
queued buffers. This makes it possible from systrace to observe
three useful points:
1. When a buffer arrives at the server
2. When the buffer is latched
3. If any buffers are dropped
In BLAST this trace point has of course been moved to the client
process. In this CL we introduce some new machinery to ATRACE and
increment an integer when transactions containing a buffer arrive
at the server. We then decrement this integer when dropping a frame or
latching a buffer.
Bug: 171232941
Test: Existing tests pass
Change-Id: I2672018e4f20d683e3249141438d0716b5af9d11
diff --git a/services/surfaceflinger/BufferStateLayer.h b/services/surfaceflinger/BufferStateLayer.h
index 69b27e4..ad00c65 100644
--- a/services/surfaceflinger/BufferStateLayer.h
+++ b/services/surfaceflinger/BufferStateLayer.h
@@ -112,6 +112,11 @@
bool onPreComposition(nsecs_t refreshStartTime) override;
uint32_t getEffectiveScalingMode() const override;
+ // See mPendingBufferTransactions
+ void incrementPendingBufferCount() override;
+ void decrementPendingBufferCount();
+ uint32_t doTransaction(uint32_t flags) override;
+
protected:
void gatherBufferInfo() override;
uint64_t getHeadFrameNumber(nsecs_t expectedPresentTime) const;
@@ -119,6 +124,7 @@
private:
friend class SlotGenerationTest;
+ inline void tracePendingBufferCount();
bool updateFrameEventHistory(const sp<Fence>& acquireFence, nsecs_t postedTime,
nsecs_t requestedPresentTime);
@@ -163,6 +169,18 @@
std::deque<std::shared_ptr<android::frametimeline::SurfaceFrame>> mPendingJankClassifications;
+ const std::string mBlastTransactionName{"BufferTX - " + mName};
+ // This integer is incremented everytime a buffer arrives at the server for this layer,
+ // and decremented when a buffer is dropped or latched. When changed the integer is exported
+ // to systrace with ATRACE_INT and mBlastTransactionName. This way when debugging perf it is
+ // possible to see when a buffer arrived at the server, and in which frame it latched.
+ //
+ // You can understand the trace this way:
+ // - If the integer increases, a buffer arrived at the server.
+ // - If the integer decreases in latchBuffer, that buffer was latched
+ // - If the integer decreases in setBuffer or doTransaction, a buffer was dropped
+ uint64_t mPendingBufferTransactions{0};
+
// TODO(marissaw): support sticky transform for LEGACY camera mode
class HwcSlotGenerator : public ClientCache::ErasedRecipient {