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.cpp b/services/surfaceflinger/BufferStateLayer.cpp
index b6c59cd..0b9caba 100644
--- a/services/surfaceflinger/BufferStateLayer.cpp
+++ b/services/surfaceflinger/BufferStateLayer.cpp
@@ -347,6 +347,12 @@
if (mCurrentState.buffer) {
mReleasePreviousBuffer = true;
+ if (mCurrentState.buffer != mDrawingState.buffer) {
+ // If mCurrentState has a buffer, and we are about to update again
+ // before swapping to drawing state, then the first buffer will be
+ // dropped and we should decrement the pending buffer count.
+ decrementPendingBufferCount();
+ }
}
mCurrentState.frameNumber = frameNumber;
@@ -629,6 +635,7 @@
if (s.buffer == nullptr) {
return BAD_VALUE;
}
+ decrementPendingBufferCount();
mPreviousBufferId = getCurrentBufferId();
mBufferInfo.mBuffer = s.buffer;
@@ -826,6 +833,32 @@
const Rect layerSize{getBounds()};
return layerSize.width() != bufferWidth || layerSize.height() != bufferHeight;
}
+
+void BufferStateLayer::incrementPendingBufferCount() {
+ mPendingBufferTransactions++;
+ tracePendingBufferCount();
+}
+
+void BufferStateLayer::decrementPendingBufferCount() {
+ mPendingBufferTransactions--;
+ tracePendingBufferCount();
+}
+
+void BufferStateLayer::tracePendingBufferCount() {
+ ATRACE_INT(mBlastTransactionName.c_str(), mPendingBufferTransactions);
+}
+
+uint32_t BufferStateLayer::doTransaction(uint32_t flags) {
+ if (mDrawingState.buffer != nullptr && mDrawingState.buffer != mBufferInfo.mBuffer) {
+ // If we are about to update mDrawingState.buffer but it has not yet latched
+ // then we will drop a buffer and should decrement the pending buffer count.
+ // This logic may not work perfectly in the face of a BufferStateLayer being the
+ // deferred side of a deferred transaction, but we don't expect this use case.
+ decrementPendingBufferCount();
+ }
+ return Layer::doTransaction(flags);
+}
+
} // namespace android
// TODO(b/129481165): remove the #pragma below and fix conversion issues