diff --git a/services/surfaceflinger/tests/unittests/VSyncDispatchRealtimeTest.cpp b/services/surfaceflinger/tests/unittests/VSyncDispatchRealtimeTest.cpp
index be49ef3..c2a7752 100644
--- a/services/surfaceflinger/tests/unittests/VSyncDispatchRealtimeTest.cpp
+++ b/services/surfaceflinger/tests/unittests/VSyncDispatchRealtimeTest.cpp
@@ -51,6 +51,7 @@
 
     void setPeriod(nsecs_t) final {}
     void resetModel() final {}
+    bool needsMoreSamples() const final { return false; }
     void dump(std::string&) const final {}
 
 private:
@@ -86,6 +87,7 @@
 
     void setPeriod(nsecs_t) final {}
     void resetModel() final {}
+    bool needsMoreSamples() const final { return false; }
     void dump(std::string&) const final {}
 
 private:
diff --git a/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp b/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp
index d940dc5..65c391d 100644
--- a/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp
+++ b/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp
@@ -47,6 +47,7 @@
     MOCK_CONST_METHOD0(currentPeriod, nsecs_t());
     MOCK_METHOD1(setPeriod, void(nsecs_t));
     MOCK_METHOD0(resetModel, void());
+    MOCK_CONST_METHOD0(needsMoreSamples, bool());
     MOCK_CONST_METHOD1(dump, void(std::string&));
 
     nsecs_t nextVSyncTime(nsecs_t timePoint) const {
diff --git a/services/surfaceflinger/tests/unittests/VSyncPredictorTest.cpp b/services/surfaceflinger/tests/unittests/VSyncPredictorTest.cpp
index fc39235..d4cd11d 100644
--- a/services/surfaceflinger/tests/unittests/VSyncPredictorTest.cpp
+++ b/services/surfaceflinger/tests/unittests/VSyncPredictorTest.cpp
@@ -73,27 +73,27 @@
 
 TEST_F(VSyncPredictorTest, reportsSamplesNeededWhenHasNoDataPoints) {
     for (auto i = 0u; i < kMinimumSamplesForPrediction; i++) {
-        EXPECT_TRUE(tracker.needsMoreSamples(mNow += mPeriod));
-        tracker.addVsyncTimestamp(mNow);
+        EXPECT_TRUE(tracker.needsMoreSamples());
+        tracker.addVsyncTimestamp(mNow += mPeriod);
     }
-    EXPECT_FALSE(tracker.needsMoreSamples(mNow));
+    EXPECT_FALSE(tracker.needsMoreSamples());
 }
 
 TEST_F(VSyncPredictorTest, reportsSamplesNeededAfterExplicitRateChange) {
     for (auto i = 0u; i < kMinimumSamplesForPrediction; i++) {
         tracker.addVsyncTimestamp(mNow += mPeriod);
     }
-    EXPECT_FALSE(tracker.needsMoreSamples(mNow));
+    EXPECT_FALSE(tracker.needsMoreSamples());
 
     auto const changedPeriod = mPeriod * 2;
     tracker.setPeriod(changedPeriod);
-    EXPECT_TRUE(tracker.needsMoreSamples(mNow));
+    EXPECT_TRUE(tracker.needsMoreSamples());
 
     for (auto i = 0u; i < kMinimumSamplesForPrediction; i++) {
-        EXPECT_TRUE(tracker.needsMoreSamples(mNow += changedPeriod));
-        tracker.addVsyncTimestamp(mNow);
+        EXPECT_TRUE(tracker.needsMoreSamples());
+        tracker.addVsyncTimestamp(mNow += changedPeriod);
     }
-    EXPECT_FALSE(tracker.needsMoreSamples(mNow));
+    EXPECT_FALSE(tracker.needsMoreSamples());
 }
 
 TEST_F(VSyncPredictorTest, transitionsToModelledPointsAfterSynthetic) {
@@ -320,20 +320,6 @@
     EXPECT_THAT(intercept, Eq(0));
 }
 
-TEST_F(VSyncPredictorTest, willBecomeInaccurateAfterA_longTimeWithNoSamples) {
-    auto const simulatedVsyncs = generateVsyncTimestamps(kMinimumSamplesForPrediction, mPeriod, 0);
-
-    for (auto const& timestamp : simulatedVsyncs) {
-        tracker.addVsyncTimestamp(timestamp);
-    }
-    auto const mNow = *simulatedVsyncs.rbegin();
-    EXPECT_FALSE(tracker.needsMoreSamples(mNow));
-
-    // TODO: would be better to decay this as a result of the variance of the samples
-    static auto constexpr aLongTimeOut = 1000000000;
-    EXPECT_TRUE(tracker.needsMoreSamples(mNow + aLongTimeOut));
-}
-
 TEST_F(VSyncPredictorTest, idealModelPredictionsBeforeRegressionModelIsBuilt) {
     auto const simulatedVsyncs =
             generateVsyncTimestamps(kMinimumSamplesForPrediction + 1, mPeriod, 0);
@@ -443,7 +429,7 @@
         // When VsyncPredictor returns the period it means that it doesn't know how to predict and
         // it needs to get more samples
         if (slope == mPeriod && intercept == 0) {
-            EXPECT_TRUE(tracker.needsMoreSamples(now));
+            EXPECT_TRUE(tracker.needsMoreSamples());
         }
     }
 }
diff --git a/services/surfaceflinger/tests/unittests/VSyncReactorTest.cpp b/services/surfaceflinger/tests/unittests/VSyncReactorTest.cpp
index a972562..6856612 100644
--- a/services/surfaceflinger/tests/unittests/VSyncReactorTest.cpp
+++ b/services/surfaceflinger/tests/unittests/VSyncReactorTest.cpp
@@ -41,6 +41,7 @@
     MOCK_CONST_METHOD0(currentPeriod, nsecs_t());
     MOCK_METHOD1(setPeriod, void(nsecs_t));
     MOCK_METHOD0(resetModel, void());
+    MOCK_CONST_METHOD0(needsMoreSamples, bool());
     MOCK_CONST_METHOD1(dump, void(std::string&));
 };
 
@@ -57,6 +58,7 @@
     nsecs_t currentPeriod() const final { return mTracker->currentPeriod(); }
     void setPeriod(nsecs_t period) final { mTracker->setPeriod(period); }
     void resetModel() final { mTracker->resetModel(); }
+    bool needsMoreSamples() const final { return mTracker->needsMoreSamples(); }
     void dump(std::string& result) const final { mTracker->dump(result); }
 
 private:
@@ -455,6 +457,83 @@
     EXPECT_FALSE(mReactor.addPresentFence(generateSignalledFenceWithTime(0)));
 }
 
+TEST_F(VSyncReactorTest, hwVsyncIsRequestedForTracker) {
+    auto time = 0;
+    bool periodFlushed = false;
+    nsecs_t const newPeriod = 4000;
+    mReactor.setPeriod(newPeriod);
+
+    static auto constexpr numSamplesWithNewPeriod = 4;
+    Sequence seq;
+    EXPECT_CALL(*mMockTracker, needsMoreSamples())
+            .Times(numSamplesWithNewPeriod - 2)
+            .InSequence(seq)
+            .WillRepeatedly(Return(true));
+    EXPECT_CALL(*mMockTracker, needsMoreSamples())
+            .Times(1)
+            .InSequence(seq)
+            .WillRepeatedly(Return(false));
+    EXPECT_CALL(*mMockTracker, addVsyncTimestamp(_)).Times(numSamplesWithNewPeriod);
+
+    EXPECT_TRUE(mReactor.addResyncSample(time += period, std::nullopt, &periodFlushed));
+
+    EXPECT_TRUE(mReactor.addResyncSample(time += period, std::nullopt, &periodFlushed));
+    // confirmed period, but predictor wants numRequest samples. This one and prior are valid.
+    EXPECT_TRUE(mReactor.addResyncSample(time += newPeriod, std::nullopt, &periodFlushed));
+    EXPECT_TRUE(mReactor.addResyncSample(time += newPeriod, std::nullopt, &periodFlushed));
+    EXPECT_FALSE(mReactor.addResyncSample(time += newPeriod, std::nullopt, &periodFlushed));
+}
+
+TEST_F(VSyncReactorTest, hwVsyncturnsOffOnConfirmationWhenTrackerDoesntRequest) {
+    auto time = 0;
+    bool periodFlushed = false;
+    nsecs_t const newPeriod = 4000;
+    mReactor.setPeriod(newPeriod);
+
+    Sequence seq;
+    EXPECT_CALL(*mMockTracker, needsMoreSamples())
+            .Times(1)
+            .InSequence(seq)
+            .WillRepeatedly(Return(false));
+    EXPECT_CALL(*mMockTracker, addVsyncTimestamp(_)).Times(2);
+
+    EXPECT_TRUE(mReactor.addResyncSample(time += period, std::nullopt, &periodFlushed));
+    EXPECT_TRUE(mReactor.addResyncSample(time += period, std::nullopt, &periodFlushed));
+    EXPECT_FALSE(mReactor.addResyncSample(time += newPeriod, std::nullopt, &periodFlushed));
+}
+
+TEST_F(VSyncReactorTest, hwVsyncIsRequestedForTrackerMultiplePeriodChanges) {
+    auto time = 0;
+    bool periodFlushed = false;
+    nsecs_t const newPeriod1 = 4000;
+    nsecs_t const newPeriod2 = 7000;
+
+    mReactor.setPeriod(newPeriod1);
+
+    Sequence seq;
+    EXPECT_CALL(*mMockTracker, needsMoreSamples())
+            .Times(4)
+            .InSequence(seq)
+            .WillRepeatedly(Return(true));
+    EXPECT_CALL(*mMockTracker, needsMoreSamples())
+            .Times(1)
+            .InSequence(seq)
+            .WillRepeatedly(Return(false));
+    EXPECT_CALL(*mMockTracker, addVsyncTimestamp(_)).Times(7);
+
+    EXPECT_TRUE(mReactor.addResyncSample(time += period, std::nullopt, &periodFlushed));
+    EXPECT_TRUE(mReactor.addResyncSample(time += period, std::nullopt, &periodFlushed));
+    // confirmed period, but predictor wants numRequest samples. This one and prior are valid.
+    EXPECT_TRUE(mReactor.addResyncSample(time += newPeriod1, std::nullopt, &periodFlushed));
+    EXPECT_TRUE(mReactor.addResyncSample(time += newPeriod1, std::nullopt, &periodFlushed));
+
+    mReactor.setPeriod(newPeriod2);
+    EXPECT_TRUE(mReactor.addResyncSample(time += newPeriod1, std::nullopt, &periodFlushed));
+    EXPECT_TRUE(mReactor.addResyncSample(time += newPeriod2, std::nullopt, &periodFlushed));
+    EXPECT_TRUE(mReactor.addResyncSample(time += newPeriod2, std::nullopt, &periodFlushed));
+    EXPECT_FALSE(mReactor.addResyncSample(time += newPeriod2, std::nullopt, &periodFlushed));
+}
+
 static nsecs_t computeWorkload(nsecs_t period, nsecs_t phase) {
     return period - phase;
 }
@@ -648,7 +727,7 @@
 
 TEST_F(VSyncReactorTest, periodChangeWithGivenVsyncPeriod) {
     bool periodFlushed = true;
-    EXPECT_CALL(*mMockTracker, addVsyncTimestamp(_)).Times(3);
+    EXPECT_CALL(*mMockTracker, addVsyncTimestamp(_)).Times(2);
     mReactor.setIgnorePresentFences(true);
 
     nsecs_t const newPeriod = 5000;
@@ -672,7 +751,7 @@
                                     kPendingLimit, true /* supportKernelIdleTimer */);
 
     bool periodFlushed = true;
-    EXPECT_CALL(*mMockTracker, addVsyncTimestamp(_)).Times(5);
+    EXPECT_CALL(*mMockTracker, addVsyncTimestamp(_)).Times(4);
     idleReactor.setIgnorePresentFences(true);
 
     // First, set the same period, which should only be confirmed when we receive two