SF: delay region sampling when short on time

In a number of janky traces, particularly at high
frame rates, we've seen the surfaceflinger thread
overrunning its time slot. In some of those cases,
the surfaceflinger thread is doing region-sampling.
This change causes region-sampling to check how much
time is left until the next vsync before deciding
whether to sample this frame. If low on time,
it will defer the sampling to a later frame.

Bug: 133779857
Test: trace inspection from scrolling in various apps
Change-Id: I92c2368e80033c1ba6e27f947a456d14db02064c

1 files changed, 1 insertions, 1 deletions

diff --git a/services/surfaceflinger/RegionSamplingThread.h b/services/surfaceflinger/RegionSamplingThread.h
index 3c6fcf3872..96ffe207e4 100644
--- a/services/surfaceflinger/RegionSamplingThread.h
+++ b/services/surfaceflinger/RegionSamplingThread.h
@@ -117,7 +117,7 @@ private:
     std::condition_variable_any mCondition;
     bool mRunning GUARDED_BY(mThreadControlMutex) = true;
     bool mSampleRequested GUARDED_BY(mThreadControlMutex) = false;
-    bool mDiscardedFrames GUARDED_BY(mThreadControlMutex) = false;
+    uint32_t mDiscardedFrames GUARDED_BY(mThreadControlMutex) = 0;
     std::chrono::nanoseconds lastSampleTime GUARDED_BY(mThreadControlMutex);
 
     std::mutex mSamplingMutex;