Report deltas as 0 instead of -1 for prediction expired display frames
Since both positive and negative values are valid for the deltas,
reporting -1 for cases where we cannot provide a delta skews the
metrics. Instead, report 0 as the delta since the jank is already
reported as unknown.
Bug: 184986864
Test: libsurfaceflinger_unittest
Change-Id: I09cbb0cb7084620038b4d5ada6c196647733bbe5
diff --git a/services/surfaceflinger/FrameTimeline/FrameTimeline.cpp b/services/surfaceflinger/FrameTimeline/FrameTimeline.cpp
index 6485265..6245019 100644
--- a/services/surfaceflinger/FrameTimeline/FrameTimeline.cpp
+++ b/services/surfaceflinger/FrameTimeline/FrameTimeline.cpp
@@ -881,10 +881,11 @@
void FrameTimeline::DisplayFrame::classifyJank(nsecs_t& deadlineDelta, nsecs_t& deltaToVsync) {
if (mPredictionState == PredictionState::Expired ||
mSurfaceFlingerActuals.presentTime == Fence::SIGNAL_TIME_INVALID) {
- // Cannot do jank classification with expired predictions or invalid signal times.
+ // Cannot do jank classification with expired predictions or invalid signal times. Set the
+ // deltas to 0 as both negative and positive deltas are used as real values.
mJankType = JankType::Unknown;
- deadlineDelta = -1;
- deltaToVsync = -1;
+ deadlineDelta = 0;
+ deltaToVsync = 0;
return;
}