commit 2739e839f88caa2bda1c072337bced240f103fc4
author Ady Abraham <adyabr@google.com> Mon Feb 14 17:42:00 2022 -0800
committer Ady Abraham <adyabr@google.com> Tue Feb 15 10:57:51 2022 -0800
tree 80b0678a21c4a3f0e8a6acb58e81e4d96c607142
parent 79bb2dc17584347412536f8faa11413b777f5a21

SF: do not latch unsignaled in early offsets

When we are in early offsets we are most likely in client composition
and/or WM animating windows. Avoid latching unsignaled buffers in this
case to avoid jank when an unsignaled buffers block newer transactions
from getting applied in the next frame.

Bug: 205153280
Test: modified TouchLatency app with long draws
Change-Id: Ice5456db1dec1feaf11f6e022a1eaaedfb26781f

services/surfaceflinger/SurfaceFlinger.cpp

diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 5991b86..80b7ce7 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -3806,7 +3806,7 @@
             prediction->presentTime - expectedPresentTime >= earlyLatchVsyncThreshold;
 }
 bool SurfaceFlinger::shouldLatchUnsignaled(const sp<Layer>& layer, const layer_state_t& state,
-                                           size_t numStates, size_t totalTXapplied) {
+                                           size_t numStates, size_t totalTXapplied) const {
     if (enableLatchUnsignaledConfig == LatchUnsignaledConfig::Disabled) {
         ALOGV("%s: false (LatchUnsignaledConfig::Disabled)", __func__);
         return false;
@@ -3824,11 +3824,22 @@
         return false;
     }
 
-    if (enableLatchUnsignaledConfig == LatchUnsignaledConfig::AutoSingleLayer &&
-        totalTXapplied > 0) {
-        ALOGV("%s: false (LatchUnsignaledConfig::AutoSingleLayer; totalTXapplied=%zu)", __func__,
-              totalTXapplied);
-        return false;
+    if (enableLatchUnsignaledConfig == LatchUnsignaledConfig::AutoSingleLayer) {
+        if (totalTXapplied > 0) {
+            ALOGV("%s: false (LatchUnsignaledConfig::AutoSingleLayer; totalTXapplied=%zu)",
+                  __func__, totalTXapplied);
+            return false;
+        }
+
+        // We don't want to latch unsignaled if are in early / client composition
+        // as it leads to jank due to RenderEngine waiting for unsignaled buffer
+        // or window animations being slow.
+        const auto isDefaultVsyncConfig = mVsyncModulator->isVsyncConfigDefault();
+        if (!isDefaultVsyncConfig) {
+            ALOGV("%s: false (LatchUnsignaledConfig::AutoSingleLayer; !isDefaultVsyncConfig)",
+                  __func__);
+            return false;
+        }
     }
 
     if (!layer->simpleBufferUpdate(state)) {