Deal with unreliable VSYNC signals due to scheduler.
We see two sources of scheduler jank when waiting for VSYNC:
- A kernfs issue that wakes up threads using a normal priority
work queue that may be delayed or have other work on it.
- The VSYNC callback from HWC is handled by a normal priority
HwBinder thread that may be delayed by other work.
Change the VrFlinger frame post thread to use an absolute timer-
based dead reckoning loop. VSYNC timestamps from the display
driver are reliable, even if the delivery of the value takes time.
Predict the VSYNC time into the future based on the last known
VSYNC time. If we see that VSYNC has not been signaled by the time
we need to post a frame to HWC we assume that the driver and/or
HWC was delayed so much that the previous frame is still pending
and skip the upcoming frame to avoid double stuffing the driver.
Bug: 65064949
Test: Extensive system tests and systraces. See bug for details.
Change-Id: Iae6c4173b8eac1d179adc3fc8004d3d475b3f156
diff --git a/libs/vr/libvrflinger/hardware_composer.h b/libs/vr/libvrflinger/hardware_composer.h
index 793c3e8..8131e50 100644
--- a/libs/vr/libvrflinger/hardware_composer.h
+++ b/libs/vr/libvrflinger/hardware_composer.h
@@ -142,9 +142,7 @@
bool operator<(const Layer& other) const {
return GetSurfaceId() < other.GetSurfaceId();
}
- bool operator<(int surface_id) const {
- return GetSurfaceId() < surface_id;
- }
+ bool operator<(int surface_id) const { return GetSurfaceId() < surface_id; }
// Sets the composer instance used by all Layer instances.
static void SetComposer(Hwc2::Composer* composer) { composer_ = composer; }
@@ -340,19 +338,23 @@
class ComposerCallback : public Hwc2::IComposerCallback {
public:
- ComposerCallback();
+ ComposerCallback() = default;
hardware::Return<void> onHotplug(Hwc2::Display display,
Connection conn) override;
hardware::Return<void> onRefresh(Hwc2::Display display) override;
hardware::Return<void> onVsync(Hwc2::Display display,
int64_t timestamp) override;
- const pdx::LocalHandle& GetVsyncEventFd() const;
- int64_t GetVsyncTime();
+
+ pdx::Status<int64_t> GetVsyncTime(Hwc2::Display display);
private:
std::mutex vsync_mutex_;
- pdx::LocalHandle vsync_event_fd_;
- int64_t vsync_time_ = -1;
+
+ struct Display {
+ pdx::LocalHandle driver_vsync_event_fd;
+ int64_t callback_vsync_timestamp{0};
+ };
+ std::array<Display, HWC_NUM_PHYSICAL_DISPLAY_TYPES> displays_;
};
HWC::Error Validate(hwc2_display_t display);
@@ -392,11 +394,10 @@
// can be interrupted by a control thread. If interrupted, these calls return
// kPostThreadInterrupted.
int ReadWaitPPState();
- int WaitForVSync(int64_t* timestamp);
+ pdx::Status<int64_t> WaitForVSync();
+ pdx::Status<int64_t> GetVSyncTime();
int SleepUntil(int64_t wakeup_timestamp);
- bool IsFramePendingInDriver() { return false; }
-
// Reconfigures the layer stack if the display surfaces changed since the last
// frame. Called only from the post thread.
bool UpdateLayerConfig();
@@ -463,6 +464,9 @@
// The timestamp of the last vsync.
int64_t last_vsync_timestamp_ = 0;
+ // The number of vsync intervals to predict since the last vsync.
+ int vsync_prediction_interval_ = 1;
+
// Vsync count since display on.
uint32_t vsync_count_ = 0;