SF: Don't bump to PERFORMANCE refresh rate with infrequent updates
Testing scenario:
1. Set brightness around 50%-55%, set dark theme.
2. Open Chrome.
3. Click search bar.
4. Can see the cursor show up.
Notice the flickering of the screen.
Explanation:
Kernel idle timer detects inactivity after 100ms, and turns the refresh rate to 60Hz.
When a cursor update happens (every 500ms), SF receives a new frame, notifies kernel,
the refresh rate bumps to 90Hz. After 100ms the kernel again decreases the refresh rate to 60Hz.
Desired goals:
Stop the flickering (eg. changing between 60-90Hz too often).
Continue having low battery impact.
Solution in this AG:
Add logic to SF to detect infrequent updates (for all layers). Description of the algorithm:
1) Store the timestamp of the last two buffers.
2) If the first buffer is older than 250 ms, detect inactivity, go into DEFAULT refresh rate.
3) EXIT: on touch event, layer requests 2 or more frames in less than 250ms.
NOTE: if the application is explicitly requesting 90Hz, SF does not override that. Idle kernel
still kicks in, and the flickering happens.
tested on Chrome v74 Beta, and messaging app.
Test: manual, b/135009095
Bug: 135718869
Change-Id: I72d8cd48b3ec900989afcf0fab1cdc3046b87274
diff --git a/services/surfaceflinger/Scheduler/LayerInfo.cpp b/services/surfaceflinger/Scheduler/LayerInfo.cpp
index 3104724..beddb9b 100644
--- a/services/surfaceflinger/Scheduler/LayerInfo.cpp
+++ b/services/surfaceflinger/Scheduler/LayerInfo.cpp
@@ -24,9 +24,10 @@
namespace android {
namespace scheduler {
-LayerInfo::LayerInfo(const std::string name, float maxRefreshRate)
+LayerInfo::LayerInfo(const std::string name, float minRefreshRate, float maxRefreshRate)
: mName(name),
mMinRefreshDuration(1e9f / maxRefreshRate),
+ mLowActivityRefreshDuration(1e9f / minRefreshRate),
mRefreshRateHistory(mMinRefreshDuration) {}
LayerInfo::~LayerInfo() = default;
@@ -47,7 +48,7 @@
const nsecs_t timeDiff = lastPresentTime - mLastPresentTime;
mLastPresentTime = lastPresentTime;
// Ignore time diff that are too high - those are stale values
- if (timeDiff > TIME_EPSILON_NS.count()) return;
+ if (timeDiff > OBSOLETE_TIME_EPSILON_NS.count()) return;
const nsecs_t refreshDuration = (timeDiff > 0) ? timeDiff : mMinRefreshDuration;
mRefreshRateHistory.insertRefreshRate(refreshDuration);
}