Add Fps class

Add a class to wrap a fps value. This is useful because across
the code we
 - convert between vsyncPeriod and fps
 - compare with tolerance (this ensures we use consistent tolerance)
 - consistent toString method

Bug: 159590486
Test: presubmit
Change-Id: Iebb77a33a2f822056642aa61bd6fac6514aa656d
diff --git a/services/surfaceflinger/Scheduler/LayerHistory.cpp b/services/surfaceflinger/Scheduler/LayerHistory.cpp
index c0d00f3..499daad 100644
--- a/services/surfaceflinger/Scheduler/LayerHistory.cpp
+++ b/services/surfaceflinger/Scheduler/LayerHistory.cpp
@@ -41,7 +41,7 @@
 
 bool isLayerActive(const Layer& layer, const LayerInfo& info, nsecs_t threshold) {
     // Layers with an explicit vote are always kept active
-    if (layer.getFrameRateForLayerTree().rate > 0) {
+    if (layer.getFrameRateForLayerTree().rate.isValid()) {
         return true;
     }
 
@@ -86,9 +86,8 @@
 
 LayerHistory::~LayerHistory() = default;
 
-void LayerHistory::registerLayer(Layer* layer, float /*lowRefreshRate*/, float highRefreshRate,
-                                 LayerVoteType type) {
-    const nsecs_t highRefreshRatePeriod = static_cast<nsecs_t>(1e9f / highRefreshRate);
+void LayerHistory::registerLayer(Layer* layer, Fps highRefreshRate, LayerVoteType type) {
+    const nsecs_t highRefreshRatePeriod = highRefreshRate.getPeriodNsecs();
     auto info = std::make_unique<LayerInfo>(layer->getName(), highRefreshRatePeriod, type);
     std::lock_guard lock(mLock);
     mLayerInfos.emplace_back(layer, std::move(info));
@@ -148,7 +147,7 @@
                 {strong->getName(), vote.type, vote.fps, vote.seamlessness, weight, layerFocused});
 
         if (CC_UNLIKELY(mTraceEnabled)) {
-            trace(layer, *info, vote.type, static_cast<int>(std::round(vote.fps)));
+            trace(layer, *info, vote.type, vote.fps.getIntValue());
         }
     }
 
@@ -177,7 +176,7 @@
                 }
             }();
 
-            if (frameRate.rate > 0 || voteType == LayerVoteType::NoVote) {
+            if (frameRate.rate.isValid() || voteType == LayerVoteType::NoVote) {
                 const auto type = layer->isVisible() ? voteType : LayerVoteType::NoVote;
                 info->setLayerVote({type, frameRate.rate, frameRate.seamlessness});
             } else {
diff --git a/services/surfaceflinger/Scheduler/LayerHistory.h b/services/surfaceflinger/Scheduler/LayerHistory.h
index 507ccc6..4214bab 100644
--- a/services/surfaceflinger/Scheduler/LayerHistory.h
+++ b/services/surfaceflinger/Scheduler/LayerHistory.h
@@ -46,7 +46,7 @@
     ~LayerHistory();
 
     // Layers are unregistered when the weak reference expires.
-    void registerLayer(Layer*, float lowRefreshRate, float highRefreshRate, LayerVoteType type);
+    void registerLayer(Layer*, Fps highRefreshRate, LayerVoteType type);
 
     // Sets the display size. Client is responsible for synchronization.
     void setDisplayArea(uint32_t displayArea) { mDisplayArea = displayArea; }
diff --git a/services/surfaceflinger/Scheduler/LayerInfo.cpp b/services/surfaceflinger/Scheduler/LayerInfo.cpp
index 66ac98a..1c0065c 100644
--- a/services/surfaceflinger/Scheduler/LayerInfo.cpp
+++ b/services/surfaceflinger/Scheduler/LayerInfo.cpp
@@ -38,7 +38,7 @@
       : mName(name),
         mHighRefreshRatePeriod(highRefreshRatePeriod),
         mDefaultVote(defaultVote),
-        mLayerVote({defaultVote, 0.0f}),
+        mLayerVote({defaultVote, Fps(0.0f)}),
         mRefreshRateHistory(name) {}
 
 void LayerInfo::setLastPresentTime(nsecs_t lastPresentTime, nsecs_t now, LayerUpdateType updateType,
@@ -91,7 +91,8 @@
 
     // Layer is considered frequent if the average frame rate is higher than the threshold
     const auto totalTime = mFrameTimes.back().queueTime - it->queueTime;
-    return (1e9f * (numFrames - 1)) / totalTime >= MIN_FPS_FOR_FREQUENT_LAYER;
+    return Fps::fromPeriodNsecs(totalTime / (numFrames - 1))
+            .greaterThanOrEqualWithMargin(MIN_FPS_FOR_FREQUENT_LAYER);
 }
 
 bool LayerInfo::isAnimating(nsecs_t now) const {
@@ -139,7 +140,7 @@
             missingPresentTime = true;
             // If there are no presentation timestamps and we haven't calculated
             // one in the past then we can't calculate the refresh rate
-            if (mLastRefreshRate.reported == 0) {
+            if (!mLastRefreshRate.reported.isValid()) {
                 return std::nullopt;
             }
             continue;
@@ -163,7 +164,7 @@
     return static_cast<nsecs_t>(averageFrameTime);
 }
 
-std::optional<float> LayerInfo::calculateRefreshRateIfPossible(nsecs_t now) {
+std::optional<Fps> LayerInfo::calculateRefreshRateIfPossible(nsecs_t now) {
     static constexpr float MARGIN = 1.0f; // 1Hz
     if (!hasEnoughDataForHeuristic()) {
         ALOGV("Not enough data");
@@ -172,7 +173,7 @@
 
     const auto averageFrameTime = calculateAverageFrameTime();
     if (averageFrameTime.has_value()) {
-        const auto refreshRate = 1e9f / *averageFrameTime;
+        const auto refreshRate = Fps::fromPeriodNsecs(*averageFrameTime);
         const bool refreshRateConsistent = mRefreshRateHistory.add(refreshRate, now);
         if (refreshRateConsistent) {
             const auto knownRefreshRate =
@@ -180,22 +181,23 @@
 
             // To avoid oscillation, use the last calculated refresh rate if it is
             // close enough
-            if (std::abs(mLastRefreshRate.calculated - refreshRate) > MARGIN &&
-                mLastRefreshRate.reported != knownRefreshRate) {
+            if (std::abs(mLastRefreshRate.calculated.getValue() - refreshRate.getValue()) >
+                        MARGIN &&
+                !mLastRefreshRate.reported.equalsWithMargin(knownRefreshRate)) {
                 mLastRefreshRate.calculated = refreshRate;
                 mLastRefreshRate.reported = knownRefreshRate;
             }
 
-            ALOGV("%s %.2fHz rounded to nearest known frame rate %.2fHz", mName.c_str(),
-                  refreshRate, mLastRefreshRate.reported);
+            ALOGV("%s %s rounded to nearest known frame rate %s", mName.c_str(),
+                  to_string(refreshRate).c_str(), to_string(mLastRefreshRate.reported).c_str());
         } else {
-            ALOGV("%s Not stable (%.2fHz) returning last known frame rate %.2fHz", mName.c_str(),
-                  refreshRate, mLastRefreshRate.reported);
+            ALOGV("%s Not stable (%s) returning last known frame rate %s", mName.c_str(),
+                  to_string(refreshRate).c_str(), to_string(mLastRefreshRate.reported).c_str());
         }
     }
 
-    return mLastRefreshRate.reported == 0 ? std::nullopt
-                                          : std::make_optional(mLastRefreshRate.reported);
+    return mLastRefreshRate.reported.isValid() ? std::make_optional(mLastRefreshRate.reported)
+                                               : std::nullopt;
 }
 
 LayerInfo::LayerVote LayerInfo::getRefreshRateVote(nsecs_t now) {
@@ -207,13 +209,13 @@
     if (isAnimating(now)) {
         ALOGV("%s is animating", mName.c_str());
         mLastRefreshRate.animatingOrInfrequent = true;
-        return {LayerHistory::LayerVoteType::Max, 0};
+        return {LayerHistory::LayerVoteType::Max, Fps(0.0f)};
     }
 
     if (!isFrequent(now)) {
         ALOGV("%s is infrequent", mName.c_str());
         mLastRefreshRate.animatingOrInfrequent = true;
-        return {LayerHistory::LayerVoteType::Min, 0};
+        return {LayerHistory::LayerVoteType::Min, Fps(0.0f)};
     }
 
     // If the layer was previously tagged as animating or infrequent, we clear
@@ -225,12 +227,12 @@
 
     auto refreshRate = calculateRefreshRateIfPossible(now);
     if (refreshRate.has_value()) {
-        ALOGV("%s calculated refresh rate: %.2f", mName.c_str(), refreshRate.value());
+        ALOGV("%s calculated refresh rate: %s", mName.c_str(), to_string(*refreshRate).c_str());
         return {LayerHistory::LayerVoteType::Heuristic, refreshRate.value()};
     }
 
     ALOGV("%s Max (can't resolve refresh rate)", mName.c_str());
-    return {LayerHistory::LayerVoteType::Max, 0};
+    return {LayerHistory::LayerVoteType::Max, Fps(0.0f)};
 }
 
 const char* LayerInfo::getTraceTag(android::scheduler::LayerHistory::LayerVoteType type) const {
@@ -256,7 +258,7 @@
     mRefreshRates.clear();
 }
 
-bool LayerInfo::RefreshRateHistory::add(float refreshRate, nsecs_t now) {
+bool LayerInfo::RefreshRateHistory::add(Fps refreshRate, nsecs_t now) {
     mRefreshRates.push_back({refreshRate, now});
     while (mRefreshRates.size() >= HISTORY_SIZE ||
            now - mRefreshRates.front().timestamp > HISTORY_DURATION.count()) {
@@ -268,7 +270,7 @@
             mHeuristicTraceTagData = makeHeuristicTraceTagData();
         }
 
-        ATRACE_INT(mHeuristicTraceTagData->average.c_str(), static_cast<int>(refreshRate));
+        ATRACE_INT(mHeuristicTraceTagData->average.c_str(), refreshRate.getIntValue());
     }
 
     return isConsistent();
@@ -279,15 +281,16 @@
 
     const auto max = std::max_element(mRefreshRates.begin(), mRefreshRates.end());
     const auto min = std::min_element(mRefreshRates.begin(), mRefreshRates.end());
-    const auto consistent = max->refreshRate - min->refreshRate <= MARGIN_FPS;
+    const auto consistent =
+            max->refreshRate.getValue() - min->refreshRate.getValue() < MARGIN_CONSISTENT_FPS;
 
     if (CC_UNLIKELY(sTraceEnabled)) {
         if (!mHeuristicTraceTagData.has_value()) {
             mHeuristicTraceTagData = makeHeuristicTraceTagData();
         }
 
-        ATRACE_INT(mHeuristicTraceTagData->max.c_str(), static_cast<int>(max->refreshRate));
-        ATRACE_INT(mHeuristicTraceTagData->min.c_str(), static_cast<int>(min->refreshRate));
+        ATRACE_INT(mHeuristicTraceTagData->max.c_str(), max->refreshRate.getIntValue());
+        ATRACE_INT(mHeuristicTraceTagData->min.c_str(), min->refreshRate.getIntValue());
         ATRACE_INT(mHeuristicTraceTagData->consistent.c_str(), consistent);
     }
 
diff --git a/services/surfaceflinger/Scheduler/LayerInfo.h b/services/surfaceflinger/Scheduler/LayerInfo.h
index e434670..9304e62 100644
--- a/services/surfaceflinger/Scheduler/LayerInfo.h
+++ b/services/surfaceflinger/Scheduler/LayerInfo.h
@@ -50,9 +50,9 @@
     // is within a threshold. If a layer is infrequent, its average refresh rate is disregarded in
     // favor of a low refresh rate.
     static constexpr size_t FREQUENT_LAYER_WINDOW_SIZE = 3;
-    static constexpr float MIN_FPS_FOR_FREQUENT_LAYER = 10.0f;
+    static constexpr Fps MIN_FPS_FOR_FREQUENT_LAYER{10.0f};
     static constexpr auto MAX_FREQUENT_LAYER_PERIOD_NS =
-            std::chrono::nanoseconds(static_cast<nsecs_t>(1e9f / MIN_FPS_FOR_FREQUENT_LAYER)) + 1ms;
+            std::chrono::nanoseconds(MIN_FPS_FOR_FREQUENT_LAYER.getPeriodNsecs()) + 1ms;
 
     friend class LayerHistoryTest;
 
@@ -60,7 +60,7 @@
     // Holds information about the layer vote
     struct LayerVote {
         LayerHistory::LayerVoteType type = LayerHistory::LayerVoteType::Heuristic;
-        float fps = 0.0f;
+        Fps fps{0.0f};
         Seamlessness seamlessness = Seamlessness::Default;
     };
 
@@ -92,7 +92,7 @@
     void setDefaultLayerVote(LayerHistory::LayerVoteType type) { mDefaultVote = type; }
 
     // Resets the layer vote to its default.
-    void resetLayerVote() { mLayerVote = {mDefaultVote, 0.0f, Seamlessness::Default}; }
+    void resetLayerVote() { mLayerVote = {mDefaultVote, Fps(0.0f), Seamlessness::Default}; }
 
     LayerVote getRefreshRateVote(nsecs_t now);
 
@@ -130,9 +130,9 @@
     // Holds information about the calculated and reported refresh rate
     struct RefreshRateHeuristicData {
         // Rate calculated on the layer
-        float calculated = 0.0f;
+        Fps calculated{0.0f};
         // Last reported rate for LayerInfo::getRefreshRate()
-        float reported = 0.0f;
+        Fps reported{0.0f};
         // Whether the last reported rate for LayerInfo::getRefreshRate()
         // was due to animation or infrequent updates
         bool animatingOrInfrequent = false;
@@ -151,18 +151,20 @@
         void clear();
 
         // Adds a new refresh rate and returns true if it is consistent
-        bool add(float refreshRate, nsecs_t now);
+        bool add(Fps refreshRate, nsecs_t now);
 
     private:
         friend class LayerHistoryTest;
 
         // Holds the refresh rate when it was calculated
         struct RefreshRateData {
-            float refreshRate = 0.0f;
+            Fps refreshRate{0.0f};
             nsecs_t timestamp = 0;
 
             bool operator<(const RefreshRateData& other) const {
-                return refreshRate < other.refreshRate;
+                // We don't need comparison with margins since we are using
+                // this to find the min and max refresh rates.
+                return refreshRate.getValue() < other.refreshRate.getValue();
             }
         };
 
@@ -180,13 +182,13 @@
         const std::string mName;
         mutable std::optional<HeuristicTraceTagData> mHeuristicTraceTagData;
         std::deque<RefreshRateData> mRefreshRates;
-        static constexpr float MARGIN_FPS = 1.0;
+        static constexpr float MARGIN_CONSISTENT_FPS = 1.0;
     };
 
     bool isFrequent(nsecs_t now) const;
     bool isAnimating(nsecs_t now) const;
     bool hasEnoughDataForHeuristic() const;
-    std::optional<float> calculateRefreshRateIfPossible(nsecs_t now);
+    std::optional<Fps> calculateRefreshRateIfPossible(nsecs_t now);
     std::optional<nsecs_t> calculateAverageFrameTime() const;
     bool isFrameTimeValid(const FrameTimeData&) const;
 
diff --git a/services/surfaceflinger/Scheduler/RefreshRateConfigs.cpp b/services/surfaceflinger/Scheduler/RefreshRateConfigs.cpp
index 83fa20e..4b7251b 100644
--- a/services/surfaceflinger/Scheduler/RefreshRateConfigs.cpp
+++ b/services/surfaceflinger/Scheduler/RefreshRateConfigs.cpp
@@ -29,10 +29,10 @@
 namespace android::scheduler {
 namespace {
 std::string formatLayerInfo(const RefreshRateConfigs::LayerRequirement& layer, float weight) {
-    return base::StringPrintf("%s (type=%s, weight=%.2f seamlessness=%s) %.2fHz",
-                              layer.name.c_str(),
+    return base::StringPrintf("%s (type=%s, weight=%.2f seamlessness=%s) %s", layer.name.c_str(),
                               RefreshRateConfigs::layerVoteTypeString(layer.vote).c_str(), weight,
-                              toString(layer.seamlessness).c_str(), layer.desiredRefreshRate);
+                              toString(layer.seamlessness).c_str(),
+                              to_string(layer.desiredRefreshRate).c_str());
 }
 } // namespace
 
@@ -41,7 +41,7 @@
 
 std::string RefreshRate::toString() const {
     return base::StringPrintf("{id=%d, hwcId=%d, fps=%.2f, width=%d, height=%d group=%d}",
-                              getConfigId().value(), hwcConfig->getId(), getFps(),
+                              getConfigId().value(), hwcConfig->getId(), getFps().getValue(),
                               hwcConfig->getWidth(), hwcConfig->getHeight(), getConfigGroup());
 }
 
@@ -64,9 +64,9 @@
 
 std::string RefreshRateConfigs::Policy::toString() const {
     return base::StringPrintf("default config ID: %d, allowGroupSwitching = %d"
-                              ", primary range: [%.2f %.2f], app request range: [%.2f %.2f]",
-                              defaultConfig.value(), allowGroupSwitching, primaryRange.min,
-                              primaryRange.max, appRequestRange.min, appRequestRange.max);
+                              ", primary range: %s, app request range: %s",
+                              defaultConfig.value(), allowGroupSwitching,
+                              primaryRange.toString().c_str(), appRequestRange.toString().c_str());
 }
 
 std::pair<nsecs_t, nsecs_t> RefreshRateConfigs::getDisplayFrames(nsecs_t layerPeriod,
@@ -144,7 +144,8 @@
     // move out the of range if layers explicitly request a different refresh
     // rate.
     const Policy* policy = getCurrentPolicyLocked();
-    const bool primaryRangeIsSingleRate = policy->primaryRange.min == policy->primaryRange.max;
+    const bool primaryRangeIsSingleRate =
+            policy->primaryRange.min.equalsWithMargin(policy->primaryRange.max);
 
     if (!globalSignals.touch && globalSignals.idle &&
         !(primaryRangeIsSingleRate && hasExplicitVoteLayers)) {
@@ -229,17 +230,18 @@
 
             // If the layer wants Max, give higher score to the higher refresh rate
             if (layer.vote == LayerVoteType::Max) {
-                const auto ratio = scores[i].first->fps / scores.back().first->fps;
+                const auto ratio =
+                        scores[i].first->fps.getValue() / scores.back().first->fps.getValue();
                 // use ratio^2 to get a lower score the more we get further from peak
                 const auto layerScore = ratio * ratio;
                 ALOGV("%s gives %s score of %.2f", formatLayerInfo(layer, weight).c_str(),
-                      scores[i].first->name.c_str(), layerScore);
+                      scores[i].first->getName().c_str(), layerScore);
                 scores[i].second += weight * layerScore;
                 continue;
             }
 
             const auto displayPeriod = scores[i].first->hwcConfig->getVsyncPeriod();
-            const auto layerPeriod = round<nsecs_t>(1e9f / layer.desiredRefreshRate);
+            const auto layerPeriod = layer.desiredRefreshRate.getPeriodNsecs();
             if (layer.vote == LayerVoteType::ExplicitDefault) {
                 const auto layerScore = [&]() {
                     // Find the actual rate the layer will render, assuming
@@ -256,7 +258,7 @@
                 }();
 
                 ALOGV("%s gives %s score of %.2f", formatLayerInfo(layer, weight).c_str(),
-                      scores[i].first->name.c_str(), layerScore);
+                      scores[i].first->getName().c_str(), layerScore);
                 scores[i].second += weight * layerScore;
                 continue;
             }
@@ -297,7 +299,7 @@
                 constexpr float kSeamedSwitchPenalty = 0.95f;
                 const float seamlessness = isSeamlessSwitch ? 1.0f : kSeamedSwitchPenalty;
                 ALOGV("%s gives %s score of %.2f", formatLayerInfo(layer, weight).c_str(),
-                      scores[i].first->name.c_str(), layerScore);
+                      scores[i].first->getName().c_str(), layerScore);
                 scores[i].second += weight * layerScore * seamlessness;
                 continue;
             }
@@ -331,7 +333,7 @@
     const RefreshRate& touchRefreshRate = getMaxRefreshRateByPolicyLocked();
 
     if (globalSignals.touch && explicitDefaultVoteLayers == 0 &&
-        bestRefreshRate->fps < touchRefreshRate.fps) {
+        bestRefreshRate->fps.lessThanWithMargin(touchRefreshRate.fps)) {
         setTouchConsidered();
         ALOGV("TouchBoost - choose %s", touchRefreshRate.getName().c_str());
         return touchRefreshRate;
@@ -347,9 +349,9 @@
     float max = begin->second;
     for (auto i = begin; i != end; ++i) {
         const auto [refreshRate, score] = *i;
-        ALOGV("%s scores %.2f", refreshRate->name.c_str(), score);
+        ALOGV("%s scores %.2f", refreshRate->getName().c_str(), score);
 
-        ATRACE_INT(refreshRate->name.c_str(), round<int>(score * 100));
+        ATRACE_INT(refreshRate->getName().c_str(), round<int>(score * 100));
 
         if (score > max * (1 + EPSILON)) {
             max = score;
@@ -433,10 +435,10 @@
 
     for (auto configId = HwcConfigIndexType(0); configId.value() < configs.size(); configId++) {
         const auto& config = configs.at(static_cast<size_t>(configId.value()));
-        const float fps = 1e9f / config->getVsyncPeriod();
         mRefreshRates.emplace(configId,
                               std::make_unique<RefreshRate>(configId, config,
-                                                            base::StringPrintf("%.2ffps", fps), fps,
+                                                            Fps::fromPeriodNsecs(
+                                                                    config->getVsyncPeriod()),
                                                             RefreshRate::ConstructorTag(0)));
         if (configId == currentConfigId) {
             mCurrentRefreshRate = mRefreshRates.at(configId).get();
@@ -463,8 +465,8 @@
         ALOGE("Default config is not in the primary range.");
         return false;
     }
-    return policy.appRequestRange.min <= policy.primaryRange.min &&
-            policy.appRequestRange.max >= policy.primaryRange.max;
+    return policy.appRequestRange.min.lessThanOrEqualWithMargin(policy.primaryRange.min) &&
+            policy.appRequestRange.max.greaterThanOrEqualWithMargin(policy.primaryRange.max);
 }
 
 status_t RefreshRateConfigs::setDisplayManagerPolicy(const Policy& policy) {
@@ -550,12 +552,9 @@
     // Filter configs based on current policy and sort based on vsync period
     const Policy* policy = getCurrentPolicyLocked();
     const auto& defaultConfig = mRefreshRates.at(policy->defaultConfig)->hwcConfig;
-    ALOGV("constructAvailableRefreshRates: default %d group %d primaryRange=[%.2f %.2f]"
-          " appRequestRange=[%.2f %.2f]",
-          policy->defaultConfig.value(), defaultConfig->getConfigGroup(), policy->primaryRange.min,
-          policy->primaryRange.max, policy->appRequestRange.min, policy->appRequestRange.max);
+    ALOGV("constructAvailableRefreshRates: %s ", policy->toString().c_str());
 
-    auto filterRefreshRates = [&](float min, float max, const char* listName,
+    auto filterRefreshRates = [&](Fps min, Fps max, const char* listName,
                                   std::vector<const RefreshRate*>* outRefreshRates) {
         getSortedRefreshRateList(
                 [&](const RefreshRate& refreshRate) REQUIRES(mLock) {
@@ -572,12 +571,12 @@
                 outRefreshRates);
 
         LOG_ALWAYS_FATAL_IF(outRefreshRates->empty(),
-                            "No matching configs for %s range: min=%.0f max=%.0f", listName, min,
-                            max);
+                            "No matching configs for %s range: min=%s max=%s", listName,
+                            to_string(min).c_str(), to_string(max).c_str());
         auto stringifyRefreshRates = [&]() -> std::string {
             std::string str;
             for (auto refreshRate : *outRefreshRates) {
-                base::StringAppendF(&str, "%s ", refreshRate->name.c_str());
+                base::StringAppendF(&str, "%s ", refreshRate->getName().c_str());
             }
             return str;
         };
@@ -590,39 +589,39 @@
                        &mAppRequestRefreshRates);
 }
 
-std::vector<float> RefreshRateConfigs::constructKnownFrameRates(
+std::vector<Fps> RefreshRateConfigs::constructKnownFrameRates(
         const std::vector<std::shared_ptr<const HWC2::Display::Config>>& configs) {
-    std::vector<float> knownFrameRates = {24.0f, 30.0f, 45.0f, 60.0f, 72.0f};
+    std::vector<Fps> knownFrameRates = {Fps(24.0f), Fps(30.0f), Fps(45.0f), Fps(60.0f), Fps(72.0f)};
     knownFrameRates.reserve(knownFrameRates.size() + configs.size());
 
     // Add all supported refresh rates to the set
     for (const auto& config : configs) {
-        const auto refreshRate = 1e9f / config->getVsyncPeriod();
+        const auto refreshRate = Fps::fromPeriodNsecs(config->getVsyncPeriod());
         knownFrameRates.emplace_back(refreshRate);
     }
 
     // Sort and remove duplicates
-    const auto frameRatesEqual = [](float a, float b) { return std::abs(a - b) <= 0.01f; };
-    std::sort(knownFrameRates.begin(), knownFrameRates.end());
+    std::sort(knownFrameRates.begin(), knownFrameRates.end(), Fps::comparesLess);
     knownFrameRates.erase(std::unique(knownFrameRates.begin(), knownFrameRates.end(),
-                                      frameRatesEqual),
+                                      Fps::EqualsWithMargin()),
                           knownFrameRates.end());
     return knownFrameRates;
 }
 
-float RefreshRateConfigs::findClosestKnownFrameRate(float frameRate) const {
-    if (frameRate <= *mKnownFrameRates.begin()) {
+Fps RefreshRateConfigs::findClosestKnownFrameRate(Fps frameRate) const {
+    if (frameRate.lessThanOrEqualWithMargin(*mKnownFrameRates.begin())) {
         return *mKnownFrameRates.begin();
     }
 
-    if (frameRate >= *std::prev(mKnownFrameRates.end())) {
+    if (frameRate.greaterThanOrEqualWithMargin(*std::prev(mKnownFrameRates.end()))) {
         return *std::prev(mKnownFrameRates.end());
     }
 
-    auto lowerBound = std::lower_bound(mKnownFrameRates.begin(), mKnownFrameRates.end(), frameRate);
+    auto lowerBound = std::lower_bound(mKnownFrameRates.begin(), mKnownFrameRates.end(), frameRate,
+                                       Fps::comparesLess);
 
-    const auto distance1 = std::abs(frameRate - *lowerBound);
-    const auto distance2 = std::abs(frameRate - *std::prev(lowerBound));
+    const auto distance1 = std::abs((frameRate.getValue() - lowerBound->getValue()));
+    const auto distance2 = std::abs((frameRate.getValue() - std::prev(lowerBound)->getValue()));
     return distance1 < distance2 ? *lowerBound : *std::prev(lowerBound);
 }
 
@@ -657,7 +656,7 @@
 
     std::lock_guard lock(mLock);
     if (frameRateOverride.frameRateHz != 0) {
-        mPreferredRefreshRateForUid[frameRateOverride.uid] = frameRateOverride.frameRateHz;
+        mPreferredRefreshRateForUid[frameRateOverride.uid] = Fps(frameRateOverride.frameRateHz);
     } else {
         mPreferredRefreshRateForUid.erase(frameRateOverride.uid);
     }
@@ -675,7 +674,7 @@
     // in DisplayManagerService.getDisplayInfoForFrameRateOverride
     constexpr float kThreshold = 0.1f;
     const auto refreshRateHz = iter->second;
-    const auto numPeriods = mCurrentRefreshRate->getFps() / refreshRateHz;
+    const auto numPeriods = mCurrentRefreshRate->getFps().getValue() / refreshRateHz.getValue();
     const auto numPeriodsRounded = std::round(numPeriods);
     if (std::abs(numPeriods - numPeriodsRounded) > kThreshold) {
         return 1;
@@ -690,7 +689,7 @@
     overrides.reserve(mPreferredRefreshRateForUid.size());
 
     for (const auto [uid, frameRate] : mPreferredRefreshRateForUid) {
-        overrides.emplace_back(FrameRateOverride{uid, frameRate});
+        overrides.emplace_back(FrameRateOverride{uid, frameRate.getValue()});
     }
 
     return overrides;
diff --git a/services/surfaceflinger/Scheduler/RefreshRateConfigs.h b/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
index 6e0c0d3..ec7ffe5 100644
--- a/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
+++ b/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
@@ -25,6 +25,7 @@
 #include <type_traits>
 
 #include "DisplayHardware/HWComposer.h"
+#include "Fps.h"
 #include "HwcStrongTypes.h"
 #include "Scheduler/SchedulerUtils.h"
 #include "Scheduler/Seamlessness.h"
@@ -64,29 +65,31 @@
 
     public:
         RefreshRate(HwcConfigIndexType configId,
-                    std::shared_ptr<const HWC2::Display::Config> config, std::string name,
-                    float fps, ConstructorTag)
-              : configId(configId), hwcConfig(config), name(std::move(name)), fps(fps) {}
+                    std::shared_ptr<const HWC2::Display::Config> config, Fps fps, ConstructorTag)
+              : configId(configId), hwcConfig(config), fps(std::move(fps)) {}
 
         RefreshRate(const RefreshRate&) = delete;
 
         HwcConfigIndexType getConfigId() const { return configId; }
         nsecs_t getVsyncPeriod() const { return hwcConfig->getVsyncPeriod(); }
         int32_t getConfigGroup() const { return hwcConfig->getConfigGroup(); }
-        const std::string& getName() const { return name; }
-        float getFps() const { return fps; }
+        std::string getName() const { return to_string(fps); }
+        Fps getFps() const { return fps; }
 
         // Checks whether the fps of this RefreshRate struct is within a given min and max refresh
-        // rate passed in. FPS_EPSILON is applied to the boundaries for approximation.
-        bool inPolicy(float minRefreshRate, float maxRefreshRate) const {
-            return (fps >= (minRefreshRate - FPS_EPSILON) && fps <= (maxRefreshRate + FPS_EPSILON));
+        // rate passed in. Margin of error is applied to the boundaries for approximation.
+        bool inPolicy(Fps minRefreshRate, Fps maxRefreshRate) const {
+            return minRefreshRate.lessThanOrEqualWithMargin(fps) &&
+                    fps.lessThanOrEqualWithMargin(maxRefreshRate);
         }
 
         bool operator!=(const RefreshRate& other) const {
             return configId != other.configId || hwcConfig != other.hwcConfig;
         }
 
-        bool operator<(const RefreshRate& other) const { return getFps() < other.getFps(); }
+        bool operator<(const RefreshRate& other) const {
+            return getFps().getValue() < other.getFps().getValue();
+        }
 
         bool operator==(const RefreshRate& other) const { return !(*this != other); }
 
@@ -96,18 +99,13 @@
         friend RefreshRateConfigs;
         friend class RefreshRateConfigsTest;
 
-        // The tolerance within which we consider FPS approximately equals.
-        static constexpr float FPS_EPSILON = 0.001f;
-
         // This config ID corresponds to the position of the config in the vector that is stored
         // on the device.
         const HwcConfigIndexType configId;
         // The config itself
         std::shared_ptr<const HWC2::Display::Config> hwcConfig;
-        // Human readable name of the refresh rate.
-        const std::string name;
         // Refresh rate in frames per second
-        const float fps = 0;
+        const Fps fps{0.0f};
     };
 
     using AllRefreshRatesMapType =
@@ -119,14 +117,19 @@
 
     public:
         struct Range {
-            float min = 0;
-            float max = std::numeric_limits<float>::max();
+            Fps min{0.0f};
+            Fps max{std::numeric_limits<float>::max()};
 
             bool operator==(const Range& other) const {
-                return min == other.min && max == other.max;
+                return min.equalsWithMargin(other.min) && max.equalsWithMargin(other.max);
             }
 
             bool operator!=(const Range& other) const { return !(*this == other); }
+
+            std::string toString() const {
+                return base::StringPrintf("[%s %s]", to_string(min).c_str(),
+                                          to_string(max).c_str());
+            }
         };
 
         // The default config, used to ensure we only initiate display config switches within the
@@ -221,7 +224,7 @@
         // Layer vote type.
         LayerVoteType vote = LayerVoteType::NoVote;
         // Layer's desired refresh rate, if applicable.
-        float desiredRefreshRate = 0.0f;
+        Fps desiredRefreshRate{0.0f};
         // If a seamless mode switch is required.
         Seamlessness seamlessness = Seamlessness::Default;
         // Layer's weight in the range of [0, 1]. The higher the weight the more impact this layer
@@ -232,7 +235,7 @@
 
         bool operator==(const LayerRequirement& other) const {
             return name == other.name && vote == other.vote &&
-                    desiredRefreshRate == other.desiredRefreshRate &&
+                    desiredRefreshRate.equalsWithMargin(other.desiredRefreshRate) &&
                     seamlessness == other.seamlessness && weight == other.weight &&
                     focused == other.focused;
         }
@@ -295,7 +298,7 @@
     static std::string layerVoteTypeString(LayerVoteType vote);
 
     // Returns a known frame rate that is the closest to frameRate
-    float findClosestKnownFrameRate(float frameRate) const;
+    Fps findClosestKnownFrameRate(Fps frameRate) const;
 
     RefreshRateConfigs(const std::vector<std::shared_ptr<const HWC2::Display::Config>>& configs,
                        HwcConfigIndexType currentConfigId);
@@ -332,7 +335,7 @@
     friend class RefreshRateConfigsTest;
 
     void constructAvailableRefreshRates() REQUIRES(mLock);
-    static std::vector<float> constructKnownFrameRates(
+    static std::vector<Fps> constructKnownFrameRates(
             const std::vector<std::shared_ptr<const HWC2::Display::Config>>& configs);
 
     void getSortedRefreshRateList(
@@ -387,7 +390,7 @@
 
     // A mapping between a UID and a preferred refresh rate that this app would
     // run at.
-    std::unordered_map<uid_t, float> mPreferredRefreshRateForUid GUARDED_BY(mLock);
+    std::unordered_map<uid_t, Fps> mPreferredRefreshRateForUid GUARDED_BY(mLock);
 
     // The min and max refresh rates supported by the device.
     // This will not change at runtime.
@@ -398,7 +401,7 @@
 
     // A sorted list of known frame rates that a Heuristic layer will choose
     // from based on the closest value.
-    const std::vector<float> mKnownFrameRates;
+    const std::vector<Fps> mKnownFrameRates;
 };
 
 } // namespace android::scheduler
diff --git a/services/surfaceflinger/Scheduler/RefreshRateStats.h b/services/surfaceflinger/Scheduler/RefreshRateStats.h
index d9e7b37..ce91a76 100644
--- a/services/surfaceflinger/Scheduler/RefreshRateStats.h
+++ b/services/surfaceflinger/Scheduler/RefreshRateStats.h
@@ -115,8 +115,10 @@
                 mConfigModesTotalTime[mCurrentConfigMode] = 0;
             }
             mConfigModesTotalTime[mCurrentConfigMode] += timeElapsedMs;
-            fps = static_cast<uint32_t>(std::round(
-                    mRefreshRateConfigs.getRefreshRateFromConfigId(mCurrentConfigMode).getFps()));
+            fps = static_cast<uint32_t>(
+                    std::round(mRefreshRateConfigs.getRefreshRateFromConfigId(mCurrentConfigMode)
+                                       .getFps()
+                                       .getValue()));
         } else {
             mScreenOffTime += timeElapsedMs;
         }
diff --git a/services/surfaceflinger/Scheduler/Scheduler.cpp b/services/surfaceflinger/Scheduler/Scheduler.cpp
index 52bf483..07411b0 100644
--- a/services/surfaceflinger/Scheduler/Scheduler.cpp
+++ b/services/surfaceflinger/Scheduler/Scheduler.cpp
@@ -510,25 +510,22 @@
 void Scheduler::registerLayer(Layer* layer) {
     if (!mLayerHistory) return;
 
-    const auto minFps = mRefreshRateConfigs.getMinRefreshRate().getFps();
     const auto maxFps = mRefreshRateConfigs.getMaxRefreshRate().getFps();
 
     if (layer->getWindowType() == InputWindowInfo::Type::STATUS_BAR) {
-        mLayerHistory->registerLayer(layer, minFps, maxFps,
-                                     scheduler::LayerHistory::LayerVoteType::NoVote);
+        mLayerHistory->registerLayer(layer, maxFps, scheduler::LayerHistory::LayerVoteType::NoVote);
     } else if (!mOptions.useContentDetection) {
         // If the content detection feature is off, all layers are registered at Max. We still keep
         // the layer history, since we use it for other features (like Frame Rate API), so layers
         // still need to be registered.
-        mLayerHistory->registerLayer(layer, minFps, maxFps,
-                                     scheduler::LayerHistory::LayerVoteType::Max);
+        mLayerHistory->registerLayer(layer, maxFps, scheduler::LayerHistory::LayerVoteType::Max);
     } else {
         if (layer->getWindowType() == InputWindowInfo::Type::WALLPAPER) {
             // Running Wallpaper at Min is considered as part of content detection.
-            mLayerHistory->registerLayer(layer, minFps, maxFps,
+            mLayerHistory->registerLayer(layer, maxFps,
                                          scheduler::LayerHistory::LayerVoteType::Min);
         } else {
-            mLayerHistory->registerLayer(layer, minFps, maxFps,
+            mLayerHistory->registerLayer(layer, maxFps,
                                          scheduler::LayerHistory::LayerVoteType::Heuristic);
         }
     }
@@ -618,14 +615,15 @@
     // TODO(145561154): cleanup the kernel idle timer implementation and the refresh rate
     // magic number
     const auto& refreshRate = mRefreshRateConfigs.getCurrentRefreshRate();
-    constexpr float FPS_THRESHOLD_FOR_KERNEL_TIMER = 65.0f;
-    if (state == TimerState::Reset && refreshRate.getFps() > FPS_THRESHOLD_FOR_KERNEL_TIMER) {
+    constexpr Fps FPS_THRESHOLD_FOR_KERNEL_TIMER{65.0f};
+    if (state == TimerState::Reset &&
+        refreshRate.getFps().greaterThanWithMargin(FPS_THRESHOLD_FOR_KERNEL_TIMER)) {
         // If we're not in performance mode then the kernel timer shouldn't do
         // anything, as the refresh rate during DPU power collapse will be the
         // same.
         resyncToHardwareVsync(true /* makeAvailable */, refreshRate.getVsyncPeriod());
     } else if (state == TimerState::Expired &&
-               refreshRate.getFps() <= FPS_THRESHOLD_FOR_KERNEL_TIMER) {
+               refreshRate.getFps().lessThanOrEqualWithMargin(FPS_THRESHOLD_FOR_KERNEL_TIMER)) {
         // Disable HW VSYNC if the timer expired, as we don't need it enabled if
         // we're not pushing frames, and if we're in PERFORMANCE mode then we'll
         // need to update the VsyncController model anyway.
diff --git a/services/surfaceflinger/Scheduler/VsyncConfiguration.cpp b/services/surfaceflinger/Scheduler/VsyncConfiguration.cpp
index aac2569..8431323 100644
--- a/services/surfaceflinger/Scheduler/VsyncConfiguration.cpp
+++ b/services/surfaceflinger/Scheduler/VsyncConfiguration.cpp
@@ -31,15 +31,10 @@
     return std::nullopt;
 }
 
-bool fpsEqualsWithMargin(float fpsA, float fpsB) {
-    static constexpr float MARGIN = 0.01f;
-    return std::abs(fpsA - fpsB) <= MARGIN;
-}
-
-std::vector<float> getRefreshRatesFromConfigs(
+std::vector<android::Fps> getRefreshRatesFromConfigs(
         const android::scheduler::RefreshRateConfigs& refreshRateConfigs) {
     const auto& allRefreshRates = refreshRateConfigs.getAllRefreshRates();
-    std::vector<float> refreshRates;
+    std::vector<android::Fps> refreshRates;
     refreshRates.reserve(allRefreshRates.size());
 
     for (const auto& [ignored, refreshRate] : allRefreshRates) {
@@ -53,12 +48,12 @@
 
 namespace android::scheduler::impl {
 
-VsyncConfiguration::VsyncConfiguration(float currentFps) : mRefreshRateFps(currentFps) {}
+VsyncConfiguration::VsyncConfiguration(Fps currentFps) : mRefreshRateFps(currentFps) {}
 
-PhaseOffsets::VsyncConfigSet VsyncConfiguration::getConfigsForRefreshRate(float fps) const {
+PhaseOffsets::VsyncConfigSet VsyncConfiguration::getConfigsForRefreshRate(Fps fps) const {
     const auto iter = std::find_if(mOffsets.begin(), mOffsets.end(),
-                                   [&fps](const std::pair<float, VsyncConfigSet>& candidateFps) {
-                                       return fpsEqualsWithMargin(fps, candidateFps.first);
+                                   [&fps](const std::pair<Fps, VsyncConfigSet>& candidateFps) {
+                                       return fps.equalsWithMargin(candidateFps.first);
                                    });
 
     if (iter != mOffsets.end()) {
@@ -67,13 +62,13 @@
 
     // Unknown refresh rate. This might happen if we get a hotplug event for an external display.
     // In this case just construct the offset.
-    ALOGW("Can't find offset for %.2f fps", fps);
-    return constructOffsets(static_cast<nsecs_t>(1e9f / fps));
+    ALOGW("Can't find offset for %s", to_string(fps).c_str());
+    return constructOffsets(fps.getPeriodNsecs());
 }
 
-void VsyncConfiguration::initializeOffsets(const std::vector<float>& refreshRates) {
+void VsyncConfiguration::initializeOffsets(const std::vector<Fps>& refreshRates) {
     for (const auto fps : refreshRates) {
-        mOffsets.emplace(fps, constructOffsets(static_cast<nsecs_t>(1e9f / fps)));
+        mOffsets.emplace(fps, constructOffsets(fps.getPeriodNsecs()));
     }
 }
 
@@ -127,7 +122,7 @@
                              .value_or(std::numeric_limits<nsecs_t>::max())) {}
 
 PhaseOffsets::PhaseOffsets(
-        const std::vector<float>& refreshRates, float currentFps, nsecs_t vsyncPhaseOffsetNs,
+        const std::vector<Fps>& refreshRates, Fps currentFps, nsecs_t vsyncPhaseOffsetNs,
         nsecs_t sfVSyncPhaseOffsetNs, std::optional<nsecs_t> earlySfOffsetNs,
         std::optional<nsecs_t> earlyGpuSfOffsetNs, std::optional<nsecs_t> earlyAppOffsetNs,
         std::optional<nsecs_t> earlyGpuAppOffsetNs, nsecs_t highFpsVsyncPhaseOffsetNs,
@@ -378,10 +373,9 @@
     validateSysprops();
 }
 
-WorkDuration::WorkDuration(const std::vector<float>& refreshRates, float currentFps,
-                           nsecs_t sfDuration, nsecs_t appDuration, nsecs_t sfEarlyDuration,
-                           nsecs_t appEarlyDuration, nsecs_t sfEarlyGpuDuration,
-                           nsecs_t appEarlyGpuDuration)
+WorkDuration::WorkDuration(const std::vector<Fps>& refreshRates, Fps currentFps, nsecs_t sfDuration,
+                           nsecs_t appDuration, nsecs_t sfEarlyDuration, nsecs_t appEarlyDuration,
+                           nsecs_t sfEarlyGpuDuration, nsecs_t appEarlyGpuDuration)
       : VsyncConfiguration(currentFps),
         mSfDuration(sfDuration),
         mAppDuration(appDuration),
diff --git a/services/surfaceflinger/Scheduler/VsyncConfiguration.h b/services/surfaceflinger/Scheduler/VsyncConfiguration.h
index c27a25d..a120e97 100644
--- a/services/surfaceflinger/Scheduler/VsyncConfiguration.h
+++ b/services/surfaceflinger/Scheduler/VsyncConfiguration.h
@@ -18,6 +18,9 @@
 
 #include <unordered_map>
 
+#include <utils/Timers.h>
+
+#include "Fps.h"
 #include "RefreshRateConfigs.h"
 #include "VsyncModulator.h"
 
@@ -35,9 +38,9 @@
 
     virtual ~VsyncConfiguration() = default;
     virtual VsyncConfigSet getCurrentConfigs() const = 0;
-    virtual VsyncConfigSet getConfigsForRefreshRate(float fps) const = 0;
+    virtual VsyncConfigSet getConfigsForRefreshRate(Fps fps) const = 0;
 
-    virtual void setRefreshRateFps(float fps) = 0;
+    virtual void setRefreshRateFps(Fps fps) = 0;
 
     virtual void dump(std::string& result) const = 0;
 };
@@ -51,10 +54,10 @@
  */
 class VsyncConfiguration : public scheduler::VsyncConfiguration {
 public:
-    explicit VsyncConfiguration(float currentFps);
+    explicit VsyncConfiguration(Fps currentFps);
 
     // Returns early, early GL, and late offsets for Apps and SF for a given refresh rate.
-    VsyncConfigSet getConfigsForRefreshRate(float fps) const override;
+    VsyncConfigSet getConfigsForRefreshRate(Fps fps) const override;
 
     // Returns early, early GL, and late offsets for Apps and SF.
     VsyncConfigSet getCurrentConfigs() const override {
@@ -63,17 +66,17 @@
 
     // This function should be called when the device is switching between different
     // refresh rates, to properly update the offsets.
-    void setRefreshRateFps(float fps) override { mRefreshRateFps = fps; }
+    void setRefreshRateFps(Fps fps) override { mRefreshRateFps = fps; }
 
     // Returns current offsets in human friendly format.
     void dump(std::string& result) const override;
 
 protected:
-    void initializeOffsets(const std::vector<float>& refreshRates);
+    void initializeOffsets(const std::vector<Fps>& refreshRates);
     virtual VsyncConfiguration::VsyncConfigSet constructOffsets(nsecs_t vsyncDuration) const = 0;
 
-    std::unordered_map<float, VsyncConfigSet> mOffsets;
-    std::atomic<float> mRefreshRateFps;
+    std::unordered_map<Fps, VsyncConfigSet, std::hash<Fps>, Fps::EqualsInBuckets> mOffsets;
+    std::atomic<Fps> mRefreshRateFps;
 };
 
 /*
@@ -86,10 +89,9 @@
 
 protected:
     // Used for unit tests
-    PhaseOffsets(const std::vector<float>& refreshRates, float currentFps,
-                 nsecs_t vsyncPhaseOffsetNs, nsecs_t sfVSyncPhaseOffsetNs,
-                 std::optional<nsecs_t> earlySfOffsetNs, std::optional<nsecs_t> earlyGpuSfOffsetNs,
-                 std::optional<nsecs_t> earlyAppOffsetNs,
+    PhaseOffsets(const std::vector<Fps>& refreshRates, Fps currentFps, nsecs_t vsyncPhaseOffsetNs,
+                 nsecs_t sfVSyncPhaseOffsetNs, std::optional<nsecs_t> earlySfOffsetNs,
+                 std::optional<nsecs_t> earlyGpuSfOffsetNs, std::optional<nsecs_t> earlyAppOffsetNs,
                  std::optional<nsecs_t> earlyGpuAppOffsetNs, nsecs_t highFpsVsyncPhaseOffsetNs,
                  nsecs_t highFpsSfVSyncPhaseOffsetNs, std::optional<nsecs_t> highFpsEarlySfOffsetNs,
                  std::optional<nsecs_t> highFpsEarlyGpuSfOffsetNs,
@@ -130,7 +132,7 @@
 
 protected:
     // Used for unit tests
-    WorkDuration(const std::vector<float>& refreshRates, float currentFps, nsecs_t sfDuration,
+    WorkDuration(const std::vector<Fps>& refreshRates, Fps currentFps, nsecs_t sfDuration,
                  nsecs_t appDuration, nsecs_t sfEarlyDuration, nsecs_t appEarlyDuration,
                  nsecs_t sfEarlyGpuDuration, nsecs_t appEarlyGpuDuration);