commit 4658e11cbe1abae691454ddcf93a06763d1bf828
author Ady Abraham <adyabr@google.com> Mon Jul 22 13:07:26 2019 -0700
committer Ady Abraham <adyabr@google.com> Tue Jul 23 01:41:52 2019 +0000
tree ddabdb04e6b80e520598ceeb4279e163c7ce2b7b
parent a92f294522951ae80e660d0745ca9e8d725ee660

SurfaceFlinger: add a sysprop for GL backpressure

In some devices where SF misses a frame in GL comp, HWC queue may
get stuffed. This causes application to block longer on dequeueBuffer
which leads to jank.

Test: 1. Open Camera
      2. Swipe horizontally to go back to previous app.

Bug: 138083790
Change-Id: I4c5963cb7ba7f9b10254c77dc7117ca3acac81cf

services/surfaceflinger/SurfaceFlinger.cpp

diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 2d31910..6166789 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -353,6 +353,11 @@
     mPropagateBackpressure = !atoi(value);
     ALOGI_IF(!mPropagateBackpressure, "Disabling backpressure propagation");
 
+    property_get("debug.sf.enable_gl_backpressure", value, "0");
+    mPropagateBackpressureClientComposition = atoi(value);
+    ALOGI_IF(mPropagateBackpressureClientComposition,
+             "Enabling backpressure propagation for Client Composition");
+
     property_get("debug.sf.enable_hwc_vds", value, "0");
     mUseHwcVirtualDisplays = atoi(value);
     ALOGI_IF(mUseHwcVirtualDisplays, "Enabling HWC virtual displays");
@@ -1670,9 +1675,9 @@
                 break;
             }
 
-            // For now, only propagate backpressure when missing a hwc frame.
-            if (hwcFrameMissed && !gpuFrameMissed) {
-                if (mPropagateBackpressure) {
+            if (frameMissed && mPropagateBackpressure) {
+                if ((hwcFrameMissed && !gpuFrameMissed) ||
+                    mPropagateBackpressureClientComposition) {
                     signalLayerUpdate();
                     break;
                 }