SF: avoid dispatching close vsyncs
When the vsync period changes, the next vsync callback might be targeting
the same vsync event, that now has a newer time based on the current
period. This means that the client might be woken up for 2 frames within
the same vsync. This change tries to avoid that by making sure that the
vsync callbacks are at least a vsync period apart minus a safe distance.
Test: new unit test
Bug: 235566681
Change-Id: Ifb9b3f8b726976452d5131c8b758d1d5ca0e3639
diff --git a/services/surfaceflinger/Scheduler/VSyncDispatchTimerQueue.cpp b/services/surfaceflinger/Scheduler/VSyncDispatchTimerQueue.cpp
index 27f4311..cc9f7cf 100644
--- a/services/surfaceflinger/Scheduler/VSyncDispatchTimerQueue.cpp
+++ b/services/surfaceflinger/Scheduler/VSyncDispatchTimerQueue.cpp
@@ -100,14 +100,8 @@
return getExpectedCallbackTime(nextVsyncTime, timing);
}
- bool const alreadyDispatchedForVsync = mLastDispatchTime &&
- ((*mLastDispatchTime + mMinVsyncDistance) >= nextVsyncTime &&
- (*mLastDispatchTime - mMinVsyncDistance) <= nextVsyncTime);
- if (alreadyDispatchedForVsync) {
- nextVsyncTime =
- tracker.nextAnticipatedVSyncTimeFrom(*mLastDispatchTime + mMinVsyncDistance);
- nextWakeupTime = nextVsyncTime - timing.workDuration - timing.readyDuration;
- }
+ nextVsyncTime = adjustVsyncIfNeeded(tracker, nextVsyncTime);
+ nextWakeupTime = nextVsyncTime - timing.workDuration - timing.readyDuration;
auto const nextReadyTime = nextVsyncTime - timing.readyDuration;
mScheduleTiming = timing;
@@ -123,6 +117,25 @@
return mWorkloadUpdateInfo.has_value();
}
+nsecs_t VSyncDispatchTimerQueueEntry::adjustVsyncIfNeeded(VSyncTracker& tracker,
+ nsecs_t nextVsyncTime) const {
+ bool const alreadyDispatchedForVsync = mLastDispatchTime &&
+ ((*mLastDispatchTime + mMinVsyncDistance) >= nextVsyncTime &&
+ (*mLastDispatchTime - mMinVsyncDistance) <= nextVsyncTime);
+ const nsecs_t currentPeriod = tracker.currentPeriod();
+ bool const nextVsyncTooClose = mLastDispatchTime &&
+ (nextVsyncTime - *mLastDispatchTime + mMinVsyncDistance) <= currentPeriod;
+ if (alreadyDispatchedForVsync) {
+ return tracker.nextAnticipatedVSyncTimeFrom(*mLastDispatchTime + mMinVsyncDistance);
+ }
+
+ if (nextVsyncTooClose) {
+ return tracker.nextAnticipatedVSyncTimeFrom(*mLastDispatchTime + currentPeriod);
+ }
+
+ return nextVsyncTime;
+}
+
void VSyncDispatchTimerQueueEntry::update(VSyncTracker& tracker, nsecs_t now) {
if (!mArmedInfo && !mWorkloadUpdateInfo) {
return;
@@ -136,7 +149,9 @@
const auto earliestReadyBy = now + mScheduleTiming.workDuration + mScheduleTiming.readyDuration;
const auto earliestVsync = std::max(earliestReadyBy, mScheduleTiming.earliestVsync);
- const auto nextVsyncTime = tracker.nextAnticipatedVSyncTimeFrom(earliestVsync);
+ const auto nextVsyncTime =
+ adjustVsyncIfNeeded(tracker, /*nextVsyncTime*/
+ tracker.nextAnticipatedVSyncTimeFrom(earliestVsync));
const auto nextReadyTime = nextVsyncTime - mScheduleTiming.readyDuration;
const auto nextWakeupTime = nextReadyTime - mScheduleTiming.workDuration;
diff --git a/services/surfaceflinger/Scheduler/VSyncDispatchTimerQueue.h b/services/surfaceflinger/Scheduler/VSyncDispatchTimerQueue.h
index 4923031..4f2f87a 100644
--- a/services/surfaceflinger/Scheduler/VSyncDispatchTimerQueue.h
+++ b/services/surfaceflinger/Scheduler/VSyncDispatchTimerQueue.h
@@ -84,6 +84,8 @@
void dump(std::string& result) const;
private:
+ nsecs_t adjustVsyncIfNeeded(VSyncTracker& tracker, nsecs_t nextVsyncTime) const;
+
const std::string mName;
const VSyncDispatch::Callback mCallback;
diff --git a/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp b/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp
index b7f968d..f660753 100644
--- a/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp
+++ b/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp
@@ -44,6 +44,8 @@
ON_CALL(*this, nextAnticipatedVSyncTimeFrom(_))
.WillByDefault(Invoke(this, &MockVSyncTracker::nextVSyncTime));
ON_CALL(*this, addVsyncTimestamp(_)).WillByDefault(Return(true));
+ ON_CALL(*this, currentPeriod())
+ .WillByDefault(Invoke(this, &MockVSyncTracker::getCurrentPeriod));
}
MOCK_METHOD1(addVsyncTimestamp, bool(nsecs_t));
@@ -62,6 +64,8 @@
return (timePoint - (timePoint % mPeriod) + mPeriod);
}
+ nsecs_t getCurrentPeriod() const { return mPeriod; }
+
protected:
nsecs_t const mPeriod;
};
@@ -393,6 +397,43 @@
EXPECT_THAT(cb1.mCalls[0], Eq(1063));
}
+TEST_F(VSyncDispatchTimerQueueTest, noCloseCallbacksAfterPeriodChange) {
+ EXPECT_CALL(mStubTracker, nextAnticipatedVSyncTimeFrom(_))
+ .Times(4)
+ .WillOnce(Return(1000))
+ .WillOnce(Return(2000))
+ .WillOnce(Return(2500))
+ .WillOnce(Return(4000));
+
+ Sequence seq;
+ EXPECT_CALL(mMockClock, alarmAt(_, 900)).InSequence(seq);
+ EXPECT_CALL(mMockClock, alarmAt(_, 1900)).InSequence(seq);
+ EXPECT_CALL(mMockClock, alarmAt(_, 3900)).InSequence(seq);
+
+ CountingCallback cb(mDispatch);
+
+ mDispatch.schedule(cb, {.workDuration = 100, .readyDuration = 0, .earliestVsync = 0});
+
+ advanceToNextCallback();
+
+ ASSERT_THAT(cb.mCalls.size(), Eq(1));
+ EXPECT_THAT(cb.mCalls[0], Eq(1000));
+
+ mDispatch.schedule(cb, {.workDuration = 100, .readyDuration = 0, .earliestVsync = 1000});
+
+ advanceToNextCallback();
+
+ ASSERT_THAT(cb.mCalls.size(), Eq(2));
+ EXPECT_THAT(cb.mCalls[1], Eq(2000));
+
+ mDispatch.schedule(cb, {.workDuration = 100, .readyDuration = 0, .earliestVsync = 2000});
+
+ advanceToNextCallback();
+
+ ASSERT_THAT(cb.mCalls.size(), Eq(3));
+ EXPECT_THAT(cb.mCalls[2], Eq(4000));
+}
+
TEST_F(VSyncDispatchTimerQueueTest, rearmsFaroutTimeoutWhenCancellingCloseOne) {
EXPECT_CALL(mStubTracker, nextAnticipatedVSyncTimeFrom(_))
.Times(4)